- 01 12月, 2016 1 次提交
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由 Baolin Wang 提交于
Alarm timers are one of the mechanisms to wake up a system from suspend, but there exist no tracepoints to analyse which process/thread armed an alarmtimer. Add tracepoints for start/cancel/expire of individual alarm timers and one for tracing the suspend time decision when to resume the system. The following trace excerpt illustrates the new mechanism: Binder:3292_2-3304 [000] d..2 149.981123: alarmtimer_cancel: alarmtimer:ffffffc1319a7800 type:REALTIME expires:1325463120000000000 now:1325376810370370245 Binder:3292_2-3304 [000] d..2 149.981136: alarmtimer_start: alarmtimer:ffffffc1319a7800 type:REALTIME expires:1325376840000000000 now:1325376810370384591 Binder:3292_9-3953 [000] d..2 150.212991: alarmtimer_cancel: alarmtimer:ffffffc1319a5a00 type:BOOTTIME expires:179552000000 now:150154008122 Binder:3292_9-3953 [000] d..2 150.213006: alarmtimer_start: alarmtimer:ffffffc1319a5a00 type:BOOTTIME expires:179551000000 now:150154025622 system_server-3000 [002] ...1 162.701940: alarmtimer_suspend: alarmtimer type:REALTIME expires:1325376840000000000 The wakeup time which is selected at suspend time allows to map it back to the task arming the timer: Binder:3292_2. [ tglx: Store alarm timer expiry time instead of some useless RTC relative information, add proper type information for wakeups which are handled via the clock_nanosleep/freezer and massage the changelog. ] Signed-off-by: NBaolin Wang <baolin.wang@linaro.org> Signed-off-by: NJohn Stultz <john.stultz@linaro.org> Acked-by: NSteven Rostedt <rostedt@goodmis.org> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Richard Cochran <richardcochran@gmail.com> Link: http://lkml.kernel.org/r/1480372524-15181-5-git-send-email-john.stultz@linaro.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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- 30 11月, 2016 1 次提交
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由 Joel Fernandes 提交于
This boot clock can be used as a tracing clock and will account for suspend time. To keep it NMI safe since we're accessing from tracing, we're not using a separate timekeeper with updates to monotonic clock and boot offset protected with seqlocks. This has the following minor side effects: (1) Its possible that a timestamp be taken after the boot offset is updated but before the timekeeper is updated. If this happens, the new boot offset is added to the old timekeeping making the clock appear to update slightly earlier: CPU 0 CPU 1 timekeeping_inject_sleeptime64() __timekeeping_inject_sleeptime(tk, delta); timestamp(); timekeeping_update(tk, TK_CLEAR_NTP...); (2) On 32-bit systems, the 64-bit boot offset (tk->offs_boot) may be partially updated. Since the tk->offs_boot update is a rare event, this should be a rare occurrence which postprocessing should be able to handle. Signed-off-by: NJoel Fernandes <joelaf@google.com> Signed-off-by: NJohn Stultz <john.stultz@linaro.org> Reviewed-by: NThomas Gleixner <tglx@linutronix.de> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/1480372524-15181-6-git-send-email-john.stultz@linaro.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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- 16 11月, 2016 3 次提交
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由 Nicolas Pitre 提交于
Some embedded systems have no use for them. This removes about 25KB from the kernel binary size when configured out. Corresponding syscalls are routed to a stub logging the attempt to use those syscalls which should be enough of a clue if they were disabled without proper consideration. They are: timer_create, timer_gettime: timer_getoverrun, timer_settime, timer_delete, clock_adjtime, setitimer, getitimer, alarm. The clock_settime, clock_gettime, clock_getres and clock_nanosleep syscalls are replaced by simple wrappers compatible with CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only which should cover the vast majority of use cases with very little code. Signed-off-by: NNicolas Pitre <nico@linaro.org> Acked-by: NRichard Cochran <richardcochran@gmail.com> Acked-by: NThomas Gleixner <tglx@linutronix.de> Acked-by: NJohn Stultz <john.stultz@linaro.org> Reviewed-by: NJosh Triplett <josh@joshtriplett.org> Cc: Paul Bolle <pebolle@tiscali.nl> Cc: linux-kbuild@vger.kernel.org Cc: netdev@vger.kernel.org Cc: Michal Marek <mmarek@suse.com> Cc: Edward Cree <ecree@solarflare.com> Link: http://lkml.kernel.org/r/1478841010-28605-7-git-send-email-nicolas.pitre@linaro.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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由 Nicolas Pitre 提交于
There is no logical relation between add_device_randomness() and posix_cpu_timers_exit(). Let's move the former to where the later is called. This way, when posix-cpu-timers.c is compiled out, there is no need to worry about not losing a call to add_device_randomness(). Signed-off-by: NNicolas Pitre <nico@linaro.org> Acked-by: NJohn Stultz <john.stultz@linaro.org> Cc: Paul Bolle <pebolle@tiscali.nl> Cc: linux-kbuild@vger.kernel.org Cc: netdev@vger.kernel.org Cc: Richard Cochran <richardcochran@gmail.com> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Michal Marek <mmarek@suse.com> Cc: Edward Cree <ecree@solarflare.com> Link: http://lkml.kernel.org/r/1478841010-28605-6-git-send-email-nicolas.pitre@linaro.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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由 Nicolas Pitre 提交于
Move the only user of alarm_setitimer to itimer.c where it is defined. This allows for making alarm_setitimer static, and dropping it from the build when __ARCH_WANT_SYS_ALARM is not defined. Signed-off-by: NNicolas Pitre <nico@linaro.org> Acked-by: NJohn Stultz <john.stultz@linaro.org> Cc: Paul Bolle <pebolle@tiscali.nl> Cc: linux-kbuild@vger.kernel.org Cc: netdev@vger.kernel.org Cc: Richard Cochran <richardcochran@gmail.com> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Michal Marek <mmarek@suse.com> Cc: Edward Cree <ecree@solarflare.com> Link: http://lkml.kernel.org/r/1478841010-28605-5-git-send-email-nicolas.pitre@linaro.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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- 26 10月, 2016 2 次提交
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由 Douglas Anderson 提交于
The documentation for schedule_timeout(), schedule_hrtimeout(), and schedule_hrtimeout_range() all claim that the routines couldn't possibly return early if the task state was TASK_UNINTERRUPTIBLE. This is simply not true since wake_up_process() will cause those routines to exit early. We cannot make schedule_[hr]timeout() loop until the timeout expires if the task state is uninterruptible because we have users which rely on the existing and designed behaviour. Make the documentation match the (correct) implementation. schedule_hrtimeout() returns -EINTR even when a uninterruptible task was woken up. This might look strange, but making the return code depend on the state is too much of an effort as it would affect all the call sites. There is no value in doing so, but we spell it out clearly in the documentation. Suggested-by: NDaniel Kurtz <djkurtz@chromium.org> Signed-off-by: NDouglas Anderson <dianders@chromium.org> Cc: huangtao@rock-chips.com Cc: heiko@sntech.de Cc: broonie@kernel.org Cc: briannorris@chromium.org Cc: Andreas Mohr <andi@lisas.de> Cc: linux-rockchip@lists.infradead.org Cc: tony.xie@rock-chips.com Cc: John Stultz <john.stultz@linaro.org> Cc: linux@roeck-us.net Cc: tskd08@gmail.com Link: http://lkml.kernel.org/r/1477065531-30342-2-git-send-email-dianders@chromium.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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由 Douglas Anderson 提交于
Users of usleep_range() expect that it will _never_ return in less time than the minimum passed parameter. However, nothing in the code ensures this, when the sleeping task is woken by wake_up_process() or any other mechanism which can wake a task from uninterruptible state. Neither usleep_range() nor schedule_hrtimeout_range*() have any protection against wakeups. schedule_hrtimeout_range*() is designed this way despite the fact that the API documentation does not mention it. msleep() already has code to handle this case since it will loop as long as there was still time left. usleep_range() has no such loop, add it. Presumably this problem was not detected before because usleep_range() is only used in a few places and the function is mostly used in contexts which are not exposed to wakeups of any form. An effort was made to look for users relying on the old behavior by looking for usleep_range() in the same file as wake_up_process(). No problems were found by this search, though it is conceivable that someone could have put the sleep and wakeup in two different files. An effort was made to ask several upstream maintainers if they were aware of people relying on wake_up_process() to wake up usleep_range(). No maintainers were aware of that but they were aware of many people relying on usleep_range() never returning before the minimum. Reported-by: NTao Huang <huangtao@rock-chips.com> Signed-off-by: NDouglas Anderson <dianders@chromium.org> Cc: heiko@sntech.de Cc: broonie@kernel.org Cc: briannorris@chromium.org Cc: Andreas Mohr <andi@lisas.de> Cc: linux-rockchip@lists.infradead.org Cc: tony.xie@rock-chips.com Cc: John Stultz <john.stultz@linaro.org> Cc: djkurtz@chromium.org Cc: linux@roeck-us.net Cc: tskd08@gmail.com Link: http://lkml.kernel.org/r/1477065531-30342-1-git-send-email-dianders@chromium.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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- 17 10月, 2016 1 次提交
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由 Tobias Klauser 提交于
Remove the set but unused variable base in alarm_clock_get to fix the following warning when building with 'W=1': kernel/time/alarmtimer.c: In function ‘alarm_timer_create’: kernel/time/alarmtimer.c:545:21: warning: variable ‘base’ set but not used [-Wunused-but-set-variable] Signed-off-by: NTobias Klauser <tklauser@distanz.ch> Cc: John Stultz <john.stultz@linaro.org> Link: http://lkml.kernel.org/r/20161017094702.10873-1-tklauser@distanz.chSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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- 11 10月, 2016 1 次提交
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由 Emese Revfy 提交于
The __latent_entropy gcc attribute can be used only on functions and variables. If it is on a function then the plugin will instrument it for gathering control-flow entropy. If the attribute is on a variable then the plugin will initialize it with random contents. The variable must be an integer, an integer array type or a structure with integer fields. These specific functions have been selected because they are init functions (to help gather boot-time entropy), are called at unpredictable times, or they have variable loops, each of which provide some level of latent entropy. Signed-off-by: NEmese Revfy <re.emese@gmail.com> [kees: expanded commit message] Signed-off-by: NKees Cook <keescook@chromium.org>
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- 05 10月, 2016 1 次提交
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由 John Stultz 提交于
In commit 27727df2 ("Avoid taking lock in NMI path with CONFIG_DEBUG_TIMEKEEPING"), I changed the logic to open-code the timekeeping_get_ns() function, but I forgot to include the unit conversion from cycles to nanoseconds, breaking the function's output, which impacts users like perf. This results in bogus perf timestamps like: swapper 0 [000] 253.427536: 111111111 cpu-clock: ffffffff810a0de6 native_safe_halt+0x6 ([kernel.kallsyms]) swapper 0 [000] 254.426573: 111111111 cpu-clock: ffffffff810a0de6 native_safe_halt+0x6 ([kernel.kallsyms]) swapper 0 [000] 254.426687: 111111111 cpu-clock: ffffffff810a0de6 native_safe_halt+0x6 ([kernel.kallsyms]) swapper 0 [000] 254.426800: 111111111 cpu-clock: ffffffff810a0de6 native_safe_halt+0x6 ([kernel.kallsyms]) swapper 0 [000] 254.426905: 111111111 cpu-clock: ffffffff810a0de6 native_safe_halt+0x6 ([kernel.kallsyms]) swapper 0 [000] 254.427022: 111111111 cpu-clock: ffffffff810a0de6 native_safe_halt+0x6 ([kernel.kallsyms]) swapper 0 [000] 254.427127: 111111111 cpu-clock: ffffffff810a0de6 native_safe_halt+0x6 ([kernel.kallsyms]) swapper 0 [000] 254.427239: 111111111 cpu-clock: ffffffff810a0de6 native_safe_halt+0x6 ([kernel.kallsyms]) swapper 0 [000] 254.427346: 111111111 cpu-clock: ffffffff810a0de6 native_safe_halt+0x6 ([kernel.kallsyms]) swapper 0 [000] 254.427463: 111111111 cpu-clock: ffffffff810a0de6 native_safe_halt+0x6 ([kernel.kallsyms]) swapper 0 [000] 255.426572: 111111111 cpu-clock: ffffffff810a0de6 native_safe_halt+0x6 ([kernel.kallsyms]) Instead of more reasonable expected timestamps like: swapper 0 [000] 39.953768: 111111111 cpu-clock: ffffffff810a0de6 native_safe_halt+0x6 ([kernel.kallsyms]) swapper 0 [000] 40.064839: 111111111 cpu-clock: ffffffff810a0de6 native_safe_halt+0x6 ([kernel.kallsyms]) swapper 0 [000] 40.175956: 111111111 cpu-clock: ffffffff810a0de6 native_safe_halt+0x6 ([kernel.kallsyms]) swapper 0 [000] 40.287103: 111111111 cpu-clock: ffffffff810a0de6 native_safe_halt+0x6 ([kernel.kallsyms]) swapper 0 [000] 40.398217: 111111111 cpu-clock: ffffffff810a0de6 native_safe_halt+0x6 ([kernel.kallsyms]) swapper 0 [000] 40.509324: 111111111 cpu-clock: ffffffff810a0de6 native_safe_halt+0x6 ([kernel.kallsyms]) swapper 0 [000] 40.620437: 111111111 cpu-clock: ffffffff810a0de6 native_safe_halt+0x6 ([kernel.kallsyms]) swapper 0 [000] 40.731546: 111111111 cpu-clock: ffffffff810a0de6 native_safe_halt+0x6 ([kernel.kallsyms]) swapper 0 [000] 40.842654: 111111111 cpu-clock: ffffffff810a0de6 native_safe_halt+0x6 ([kernel.kallsyms]) swapper 0 [000] 40.953772: 111111111 cpu-clock: ffffffff810a0de6 native_safe_halt+0x6 ([kernel.kallsyms]) swapper 0 [000] 41.064881: 111111111 cpu-clock: ffffffff810a0de6 native_safe_halt+0x6 ([kernel.kallsyms]) Add the proper use of timekeeping_delta_to_ns() to convert the cycle delta to nanoseconds as needed. Thanks to Brendan and Alexei for finding this quickly after the v4.8 release. Unfortunately the problematic commit has landed in some -stable trees so they'll need this fix as well. Many apologies for this mistake. I'll be looking to add a perf-clock sanity test to the kselftest timers tests soon. Fixes: 27727df2 "timekeeping: Avoid taking lock in NMI path with CONFIG_DEBUG_TIMEKEEPING" Reported-by: NBrendan Gregg <bgregg@netflix.com> Reported-by: NAlexei Starovoitov <alexei.starovoitov@gmail.com> Tested-and-reviewed-by: NMathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: NJohn Stultz <john.stultz@linaro.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: stable <stable@vger.kernel.org> Cc: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/1475636148-26539-1-git-send-email-john.stultz@linaro.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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- 13 9月, 2016 1 次提交
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由 Wanpeng Li 提交于
can_stop_full_tick() has no check for offline cpus. So it allows to stop the tick on an offline cpu from the interrupt return path, which is wrong and subsequently makes irq_work_needs_cpu() warn about being called for an offline cpu. Commit f7ea0fd6 ("tick: Don't invoke tick_nohz_stop_sched_tick() if the cpu is offline") added prevention for can_stop_idle_tick(), but forgot to do the same in can_stop_full_tick(). Add it. [ tglx: Massaged changelog ] Signed-off-by: NWanpeng Li <wanpeng.li@hotmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/r/1473245473-4463-1-git-send-email-wanpeng.li@hotmail.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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- 02 9月, 2016 1 次提交
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由 Wanpeng Li 提交于
tick_nohz_start_idle() is prevented to be called if the idle tick can't be stopped since commit 1f3b0f82 ("tick/nohz: Optimize nohz idle enter"). As a result, after suspend/resume the host machine, full dynticks kvm guest will softlockup: NMI watchdog: BUG: soft lockup - CPU#0 stuck for 26s! [swapper/0:0] Call Trace: default_idle+0x31/0x1a0 arch_cpu_idle+0xf/0x20 default_idle_call+0x2a/0x50 cpu_startup_entry+0x39b/0x4d0 rest_init+0x138/0x140 ? rest_init+0x5/0x140 start_kernel+0x4c1/0x4ce ? set_init_arg+0x55/0x55 ? early_idt_handler_array+0x120/0x120 x86_64_start_reservations+0x24/0x26 x86_64_start_kernel+0x142/0x14f In addition, cat /proc/stat | grep cpu in guest or host: cpu 398 16 5049 15754 5490 0 1 46 0 0 cpu0 206 5 450 0 0 0 1 14 0 0 cpu1 81 0 3937 3149 1514 0 0 9 0 0 cpu2 45 6 332 6052 2243 0 0 11 0 0 cpu3 65 2 328 6552 1732 0 0 11 0 0 The idle and iowait states are weird 0 for cpu0(housekeeping). The bug is present in both guest and host kernels, and they both have cpu0's idle and iowait states issue, however, host kernel's suspend/resume path etc will touch watchdog to avoid the softlockup. - The watchdog will not be touched in tick_nohz_stop_idle path (need be touched since the scheduler stall is expected) if idle_active flags are not detected. - The idle and iowait states will not be accounted when exit idle loop (resched or interrupt) if idle start time and idle_active flags are not set. This patch fixes it by reverting commit 1f3b0f82 since can't stop idle tick doesn't mean can't be idle. Fixes: 1f3b0f82 ("tick/nohz: Optimize nohz idle enter") Signed-off-by: NWanpeng Li <wanpeng.li@hotmail.com> Cc: Sanjeev Yadav<sanjeev.yadav@spreadtrum.com> Cc: Gaurav Jindal<gaurav.jindal@spreadtrum.com> Cc: stable@vger.kernel.org Cc: kvm@vger.kernel.org Cc: Radim Krčmář <rkrcmar@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Paolo Bonzini <pbonzini@redhat.com> Link: http://lkml.kernel.org/r/1472798303-4154-1-git-send-email-wanpeng.li@hotmail.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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- 01 9月, 2016 5 次提交
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由 Vegard Nossum 提交于
I ran into this: ================================================================================ UBSAN: Undefined behaviour in kernel/time/hrtimer.c:310:16 signed integer overflow: 9223372036854775807 + 50000 cannot be represented in type 'long long int' CPU: 2 PID: 4798 Comm: trinity-c2 Not tainted 4.8.0-rc1+ #91 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.9.3-0-ge2fc41e-prebuilt.qemu-project.org 04/01/2014 0000000000000000 ffff88010ce6fb88 ffffffff82344740 0000000041b58ab3 ffffffff84f97a20 ffffffff82344694 ffff88010ce6fbb0 ffff88010ce6fb60 000000000000c350 ffff88010ce6f968 dffffc0000000000 ffffffff857bc320 Call Trace: [<ffffffff82344740>] dump_stack+0xac/0xfc [<ffffffff82344694>] ? _atomic_dec_and_lock+0xc4/0xc4 [<ffffffff8242df78>] ubsan_epilogue+0xd/0x8a [<ffffffff8242e6b4>] handle_overflow+0x202/0x23d [<ffffffff8242e4b2>] ? val_to_string.constprop.6+0x11e/0x11e [<ffffffff8236df71>] ? timerqueue_add+0x151/0x410 [<ffffffff81485c48>] ? hrtimer_start_range_ns+0x3b8/0x1380 [<ffffffff81795631>] ? memset+0x31/0x40 [<ffffffff8242e6fd>] __ubsan_handle_add_overflow+0xe/0x10 [<ffffffff81488ac9>] hrtimer_nanosleep+0x5d9/0x790 [<ffffffff814884f0>] ? hrtimer_init_sleeper+0x80/0x80 [<ffffffff813a9ffb>] ? __might_sleep+0x5b/0x260 [<ffffffff8148be10>] common_nsleep+0x20/0x30 [<ffffffff814906c7>] SyS_clock_nanosleep+0x197/0x210 [<ffffffff81490530>] ? SyS_clock_getres+0x150/0x150 [<ffffffff823c7113>] ? __this_cpu_preempt_check+0x13/0x20 [<ffffffff8162ef60>] ? __context_tracking_exit.part.3+0x30/0x1b0 [<ffffffff81490530>] ? SyS_clock_getres+0x150/0x150 [<ffffffff81007bd3>] do_syscall_64+0x1b3/0x4b0 [<ffffffff845f85aa>] entry_SYSCALL64_slow_path+0x25/0x25 ================================================================================ Add a new ktime_add_unsafe() helper which doesn't check for overflow, but doesn't throw a UBSAN warning when it does overflow either. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Prarit Bhargava <prarit@redhat.com> Signed-off-by: NVegard Nossum <vegard.nossum@oracle.com> Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
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由 Vegard Nossum 提交于
I ran into this: ================================================================================ UBSAN: Undefined behaviour in kernel/time/time.c:783:2 signed integer overflow: 5273 + 9223372036854771711 cannot be represented in type 'long int' CPU: 0 PID: 17363 Comm: trinity-c0 Not tainted 4.8.0-rc1+ #88 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.9.3-0-ge2fc41e-prebuilt.qemu-project.org 04/01/2014 0000000000000000 ffff88011457f8f0 ffffffff82344f50 0000000041b58ab3 ffffffff84f98080 ffffffff82344ea4 ffff88011457f918 ffff88011457f8c8 ffff88011457f8e0 7fffffffffffefff ffff88011457f6d8 dffffc0000000000 Call Trace: [<ffffffff82344f50>] dump_stack+0xac/0xfc [<ffffffff82344ea4>] ? _atomic_dec_and_lock+0xc4/0xc4 [<ffffffff8242f4c8>] ubsan_epilogue+0xd/0x8a [<ffffffff8242fc04>] handle_overflow+0x202/0x23d [<ffffffff8242fa02>] ? val_to_string.constprop.6+0x11e/0x11e [<ffffffff823c7837>] ? debug_smp_processor_id+0x17/0x20 [<ffffffff8131b581>] ? __sigqueue_free.part.13+0x51/0x70 [<ffffffff8146d4e0>] ? rcu_is_watching+0x110/0x110 [<ffffffff8242fc4d>] __ubsan_handle_add_overflow+0xe/0x10 [<ffffffff81476ef8>] timespec64_add_safe+0x298/0x340 [<ffffffff81476c60>] ? timespec_add_safe+0x330/0x330 [<ffffffff812f7990>] ? wait_noreap_copyout+0x1d0/0x1d0 [<ffffffff8184bf18>] poll_select_set_timeout+0xf8/0x170 [<ffffffff8184be20>] ? poll_schedule_timeout+0x2b0/0x2b0 [<ffffffff813aa9bb>] ? __might_sleep+0x5b/0x260 [<ffffffff833c8a87>] __sys_recvmmsg+0x107/0x790 [<ffffffff833c8980>] ? SyS_recvmsg+0x20/0x20 [<ffffffff81486378>] ? hrtimer_start_range_ns+0x3b8/0x1380 [<ffffffff845f8bfb>] ? _raw_spin_unlock_irqrestore+0x3b/0x60 [<ffffffff8148bcea>] ? do_setitimer+0x39a/0x8e0 [<ffffffff813aa9bb>] ? __might_sleep+0x5b/0x260 [<ffffffff833c9110>] ? __sys_recvmmsg+0x790/0x790 [<ffffffff833c91e9>] SyS_recvmmsg+0xd9/0x160 [<ffffffff833c9110>] ? __sys_recvmmsg+0x790/0x790 [<ffffffff823c7853>] ? __this_cpu_preempt_check+0x13/0x20 [<ffffffff8162f680>] ? __context_tracking_exit.part.3+0x30/0x1b0 [<ffffffff833c9110>] ? __sys_recvmmsg+0x790/0x790 [<ffffffff81007bd3>] do_syscall_64+0x1b3/0x4b0 [<ffffffff845f936a>] entry_SYSCALL64_slow_path+0x25/0x25 ================================================================================ Line 783 is this: 783 set_normalized_timespec64(&res, lhs.tv_sec + rhs.tv_sec, 784 lhs.tv_nsec + rhs.tv_nsec); In other words, since lhs.tv_sec and rhs.tv_sec are both time64_t, this is a signed addition which will cause undefined behaviour on overflow. Note that this is not currently a huge concern since the kernel should be built with -fno-strict-overflow by default, but could be a problem in the future, a problem with older compilers, or other compilers than gcc. The easiest way to avoid the overflow is to cast one of the arguments to unsigned (so the addition will be done using unsigned arithmetic). Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Prarit Bhargava <prarit@redhat.com> Signed-off-by: NVegard Nossum <vegard.nossum@oracle.com> Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
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由 Ruchi Kandoi 提交于
In addition to keeping a histogram of suspend times, also print out the time spent in suspend to dmesg. This helps to keep track of suspend time while debugging using kernel logs. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Prarit Bhargava <prarit@redhat.com> Signed-off-by: NRuchi Kandoi <kandoiruchi@google.com> [jstultz: Tweaked commit message] Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
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由 Kyle Walker 提交于
Clocksources don't get the VALID_FOR_HRES flag until they have been checked by a watchdog. However, when using an override, the clocksource_select logic will clear the override value if the clocksource is not marked VALID_FOR_HRES during that inititial check. When using the boot arguments clocksource=<foo>, this selection can run before the watchdog, and can cause the override to be incorrectly cleared. To address this condition, the override_name is only invalidated for unstable clocksources. Otherwise, the override is left intact until after the watchdog has validated the clocksource as stable/unstable. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: NKyle Walker <kwalker@redhat.com> Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
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由 Pratyush Patel 提交于
Fix a minor spelling error. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Prarit Bhargava <prarit@redhat.com> Signed-off-by: NPratyush Patel <pratyushpatel.1995@gmail.com> [jstultz: Added commit message] Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
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- 24 8月, 2016 2 次提交
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由 John Stultz 提交于
It was reported that hibernation could fail on the 2nd attempt, where the system hangs at hibernate() -> syscore_resume() -> i8237A_resume() -> claim_dma_lock(), because the lock has already been taken. However there is actually no other process would like to grab this lock on that problematic platform. Further investigation showed that the problem is triggered by setting /sys/power/pm_trace to 1 before the 1st hibernation. Since once pm_trace is enabled, the rtc becomes unmeaningful after suspend, and meanwhile some BIOSes would like to adjust the 'invalid' RTC (e.g, smaller than 1970) to the release date of that motherboard during POST stage, thus after resumed, it may seem that the system had a significant long sleep time which is a completely meaningless value. Then in timekeeping_resume -> tk_debug_account_sleep_time, if the bit31 of the sleep time happened to be set to 1, fls() returns 32 and we add 1 to sleep_time_bin[32], which causes an out of bounds array access and therefor memory being overwritten. As depicted by System.map: 0xffffffff81c9d080 b sleep_time_bin 0xffffffff81c9d100 B dma_spin_lock the dma_spin_lock.val is set to 1, which caused this problem. This patch adds a sanity check in tk_debug_account_sleep_time() to ensure we don't index past the sleep_time_bin array. [jstultz: Problem diagnosed and original patch by Chen Yu, I've solved the issue slightly differently, but borrowed his excelent explanation of the issue here.] Fixes: 5c83545f "power: Add option to log time spent in suspend" Reported-by: NJanek Kozicki <cosurgi@gmail.com> Reported-by: NChen Yu <yu.c.chen@intel.com> Signed-off-by: NJohn Stultz <john.stultz@linaro.org> Cc: linux-pm@vger.kernel.org Cc: Peter Zijlstra <peterz@infradead.org> Cc: Xunlei Pang <xpang@redhat.com> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: stable <stable@vger.kernel.org> Cc: Zhang Rui <rui.zhang@intel.com> Link: http://lkml.kernel.org/r/1471993702-29148-3-git-send-email-john.stultz@linaro.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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由 John Stultz 提交于
When I added some extra sanity checking in timekeeping_get_ns() under CONFIG_DEBUG_TIMEKEEPING, I missed that the NMI safe __ktime_get_fast_ns() method was using timekeeping_get_ns(). Thus the locking added to the debug checks broke the NMI-safety of __ktime_get_fast_ns(). This patch open-codes the timekeeping_get_ns() logic for __ktime_get_fast_ns(), so can avoid any deadlocks in NMI. Fixes: 4ca22c26 "timekeeping: Add warnings when overflows or underflows are observed" Reported-by: NSteven Rostedt <rostedt@goodmis.org> Reported-by: NPeter Zijlstra <peterz@infradead.org> Signed-off-by: NJohn Stultz <john.stultz@linaro.org> Cc: stable <stable@vger.kernel.org> Link: http://lkml.kernel.org/r/1471993702-29148-2-git-send-email-john.stultz@linaro.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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- 09 8月, 2016 1 次提交
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由 Chris Metcalf 提交于
The tick_nohz_stop_sched_tick() routine is not properly canceling the sched timer when nothing is pending, because get_next_timer_interrupt() is no longer returning KTIME_MAX in that case. This causes periodic interrupts when none are needed. When determining the next interrupt time, we first use __next_timer_interrupt() to get the first expiring timer in the timer wheel. If no timer is found, we return the base clock value plus NEXT_TIMER_MAX_DELTA to indicate there is no timer in the timer wheel. Back in get_next_timer_interrupt(), we set the "expires" value by converting the timer wheel expiry (in ticks) to a nsec value. But we don't want to do this if the timer wheel expiry value indicates no timer; we want to return KTIME_MAX. Prior to commit 500462a9 ("timers: Switch to a non-cascading wheel") we checked base->active_timers to see if any timers were active, and if not, we didn't touch the expiry value and so properly returned KTIME_MAX. Now we don't have active_timers. To fix this, we now just check the timer wheel expiry value to see if it is "now + NEXT_TIMER_MAX_DELTA", and if it is, we don't try to compute a new value based on it, but instead simply let the KTIME_MAX value in expires remain. Fixes: 500462a9 "timers: Switch to a non-cascading wheel" Signed-off-by: NChris Metcalf <cmetcalf@mellanox.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Christoph Lameter <cl@linux.com> Cc: John Stultz <john.stultz@linaro.org> Link: http://lkml.kernel.org/r/1470688147-22287-1-git-send-email-cmetcalf@mellanox.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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- 19 7月, 2016 2 次提交
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由 Gaurav Jindal 提交于
tick_nohz_start_idle is called before checking whether the idle tick can be stopped. If the tick cannot be stopped, calling tick_nohz_start_idle() is pointless and just wasting CPU cycles. Only invoke tick_nohz_start_idle() when can_stop_idle_tick() returns true. A short one minute observation of the effect on ARM64 shows a reduction of calls by 1.5% thus optimizing the idle entry sequence. [tglx: Massaged changelog ] Co-developed-by: Sanjeev Yadav<sanjeev.yadav@spreadtrum.com> Signed-off-by: Gaurav Jindal<gaurav.jindal@spreadtrum.com> Link: http://lkml.kernel.org/r/20160714120416.GB21099@gaurav.jindal@spreadtrum.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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由 Ben Dooks 提交于
The clockevents_subsys struct is used for sysfs support and is not declared or used outside the file it is defined in. Fix the following warning by making it static: kernel/time/clockevents.c:648:17: warning: symbol 'clockevents_subsys' was not declared. Should it be static? Signed-off-by: NBen Dooks <ben.dooks@codethink.co.uk> Cc: linux-kernel@lists.codethink.co.uk Link: http://lkml.kernel.org/r/1466178974-7105-1-git-send-email-ben.dooks@codethink.co.ukSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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- 15 7月, 2016 2 次提交
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由 Richard Cochran 提交于
When tearing down, call timers_dead_cpu() before notify_dead(). There is a hidden dependency between: - timers - block multiqueue - rcutree If timers_dead_cpu() comes later than blk_mq_queue_reinit_notify() that latter function causes a RCU stall. Signed-off-by: NRichard Cochran <rcochran@linutronix.de> Signed-off-by: NAnna-Maria Gleixner <anna-maria@linutronix.de> Reviewed-by: NSebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: John Stultz <john.stultz@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160713153337.566790058@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Thomas Gleixner 提交于
Split out the clockevents callbacks instead of piggybacking them on hrtimers. This gets rid of a POST_DEAD user. See commit: 54e88fad ("sched: Make sure timers have migrated before killing the migration_thread") We just move the callback state to the proper place in the state machine. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Signed-off-by: NAnna-Maria Gleixner <anna-maria@linutronix.de> Reviewed-by: NSebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160713153337.485419196@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
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- 11 7月, 2016 1 次提交
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由 Alexey Dobriyan 提交于
Variable "now" seems to be genuinely used unintialized if branch if (CPUCLOCK_PERTHREAD(timer->it_clock)) { is not taken and branch if (unlikely(sighand == NULL)) { is taken. In this case the process has been reaped and the timer is marked as disarmed anyway. So none of the postprocessing of the sample is required. Return right away. Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/20160707223911.GA26483@p183.telecom.bySigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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- 07 7月, 2016 12 次提交
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由 Anna-Maria Gleixner 提交于
The existing optimization for same expiry time in mod_timer() checks whether the timer expiry time is the same as the new requested expiry time. In the old timer wheel implementation this does not take the slack batching into account, neither does the new implementation evaluate whether the new expiry time will requeue the timer to the same bucket. To optimize that, we can calculate the resulting bucket and check if the new expiry time is different from the current expiry time. This calculation happens outside the base lock held region. If the resulting bucket is the same we can avoid taking the base lock and requeueing the timer. If the timer needs to be requeued then we have to check under the base lock whether the base time has changed between the lockless calculation and taking the lock. If it has changed we need to recalculate under the lock. This optimization takes effect for timers which are enqueued into the less granular wheel levels (1 and above). With a simple test case the functionality has been verified: Before After Match: 5.5% 86.6% Requeue: 94.5% 13.4% Recalc: <0.01% In the non optimized case the timer is requeued in 94.5% of the cases. With the index optimization in place the requeue rate drops to 13.4%. The case where the lockless index calculation has to be redone is less than 0.01%. With a real world test case (networking) we observed the following changes: Before After Match: 97.8% 99.7% Requeue: 2.2% 0.3% Recalc: <0.001% That means two percent fewer lock/requeue/unlock operations done in one of the hot path use cases of timers. Signed-off-by: NAnna-Maria Gleixner <anna-maria@linutronix.de> Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Chris Mason <clm@fb.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: George Spelvin <linux@sciencehorizons.net> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Len Brown <lenb@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160704094342.778527749@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Anna-Maria Gleixner 提交于
For further optimizations we need to seperate index calculation from queueing. No functional change. Signed-off-by: NAnna-Maria Gleixner <anna-maria@linutronix.de> Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Chris Mason <clm@fb.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: George Spelvin <linux@sciencehorizons.net> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Len Brown <lenb@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160704094342.691159619@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Thomas Gleixner 提交于
With the wheel forwading in place and with the HZ=1000 4ms folding we can avoid running the softirq at all. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Chris Mason <clm@fb.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: George Spelvin <linux@sciencehorizons.net> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Len Brown <lenb@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160704094342.607650550@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Thomas Gleixner 提交于
The wheel clock is stale when a CPU goes into a long idle sleep. This has the side effect that timers which are queued end up in the outer wheel levels. That results in coarser granularity. To solve this, we keep track of the idle state and forward the wheel clock whenever possible. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Chris Mason <clm@fb.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: George Spelvin <linux@sciencehorizons.net> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Len Brown <lenb@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160704094342.512039360@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Thomas Gleixner 提交于
This was a failed attempt to optimize the timer expiry in idle, which was disabled and never revisited. Remove the cruft. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Chris Mason <clm@fb.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: George Spelvin <linux@sciencehorizons.net> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Len Brown <lenb@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160704094342.431073782@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Anna-Maria Gleixner 提交于
After a NOHZ idle sleep the timer wheel must be forwarded to current jiffies. There might be expired timers so the current code loops and checks the expired buckets for timers. This can take quite some time for long NOHZ idle periods. The pending bitmask in the timer base allows us to do a quick search for the next expiring timer and therefore a fast forward of the base time which prevents pointless long lasting loops. For a 3 seconds idle sleep this reduces the catchup time from ~1ms to 5us. Signed-off-by: NAnna-Maria Gleixner <anna-maria@linutronix.de> Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Chris Mason <clm@fb.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: George Spelvin <linux@sciencehorizons.net> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Len Brown <lenb@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160704094342.351296290@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Anna-Maria Gleixner 提交于
Move __run_timers() below __next_timer_interrupt() and next_pending_bucket() in preparation for __run_timers() NOHZ optimization. No functional change. Signed-off-by: NAnna-Maria Gleixner <anna-maria@linutronix.de> Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Chris Mason <clm@fb.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: George Spelvin <linux@sciencehorizons.net> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Len Brown <lenb@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160704094342.271872665@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Thomas Gleixner 提交于
We now have implicit batching in the timer wheel. The slack API is no longer used, so remove it. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: Andrew F. Davis <afd@ti.com> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Chris Mason <clm@fb.com> Cc: David S. Miller <davem@davemloft.net> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: George Spelvin <linux@sciencehorizons.net> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Jaehoon Chung <jh80.chung@samsung.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: John Stultz <john.stultz@linaro.org> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Len Brown <lenb@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mathias Nyman <mathias.nyman@intel.com> Cc: Pali Rohár <pali.rohar@gmail.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Sebastian Reichel <sre@kernel.org> Cc: Ulf Hansson <ulf.hansson@linaro.org> Cc: linux-block@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: linux-mmc@vger.kernel.org Cc: linux-pm@vger.kernel.org Cc: linux-usb@vger.kernel.org Cc: netdev@vger.kernel.org Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160704094342.189813118@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Thomas Gleixner 提交于
The current timer wheel has some drawbacks: 1) Cascading: Cascading can be an unbound operation and is completely pointless in most cases because the vast majority of the timer wheel timers are canceled or rearmed before expiration. (They are used as timeout safeguards, not as real timers to measure time.) 2) No fast lookup of the next expiring timer: In NOHZ scenarios the first timer soft interrupt after a long NOHZ period must fast forward the base time to the current value of jiffies. As we have no way to find the next expiring timer fast, the code loops linearly and increments the base time one by one and checks for expired timers in each step. This causes unbound overhead spikes exactly in the moment when we should wake up as fast as possible. After a thorough analysis of real world data gathered on laptops, workstations, webservers and other machines (thanks Chris!) I came to the conclusion that the current 'classic' timer wheel implementation can be modified to address the above issues. The vast majority of timer wheel timers is canceled or rearmed before expiry. Most of them are timeouts for networking and other I/O tasks. The nature of timeouts is to catch the exception from normal operation (TCP ack timed out, disk does not respond, etc.). For these kinds of timeouts the accuracy of the timeout is not really a concern. Timeouts are very often approximate worst-case values and in case the timeout fires, we already waited for a long time and performance is down the drain already. The few timers which actually expire can be split into two categories: 1) Short expiry times which expect halfways accurate expiry 2) Long term expiry times are inaccurate today already due to the batching which is done for NOHZ automatically and also via the set_timer_slack() API. So for long term expiry timers we can avoid the cascading property and just leave them in the less granular outer wheels until expiry or cancelation. Timers which are armed with a timeout larger than the wheel capacity are no longer cascaded. We expire them with the longest possible timeout (6+ days). We have not observed such timeouts in our data collection, but at least we handle them, applying the rule of the least surprise. To avoid extending the wheel levels for HZ=1000 so we can accomodate the longest observed timeouts (5 days in the network conntrack code) we reduce the first level granularity on HZ=1000 to 4ms, which effectively is the same as the HZ=250 behaviour. From our data analysis there is nothing which relies on that 1ms granularity and as a side effect we get better batching and timer locality for the networking code as well. Contrary to the classic wheel the granularity of the next wheel is not the capacity of the first wheel. The granularities of the wheels are in the currently chosen setting 8 times the granularity of the previous wheel. So for HZ=250 we end up with the following granularity levels: Level Offset Granularity Range 0 0 4 ms 0 ms - 252 ms 1 64 32 ms 256 ms - 2044 ms (256ms - ~2s) 2 128 256 ms 2048 ms - 16380 ms (~2s - ~16s) 3 192 2048 ms (~2s) 16384 ms - 131068 ms (~16s - ~2m) 4 256 16384 ms (~16s) 131072 ms - 1048572 ms (~2m - ~17m) 5 320 131072 ms (~2m) 1048576 ms - 8388604 ms (~17m - ~2h) 6 384 1048576 ms (~17m) 8388608 ms - 67108863 ms (~2h - ~18h) 7 448 8388608 ms (~2h) 67108864 ms - 536870911 ms (~18h - ~6d) That's a worst case inaccuracy of 12.5% for the timers which are queued at the beginning of a level. So the new wheel concept addresses the old issues: 1) Cascading is avoided completely 2) By keeping the timers in the bucket until expiry/cancelation we can track the buckets which have timers enqueued in a bucket bitmap and therefore can look up the next expiring timer very fast and O(1). A further benefit of the concept is that the slack calculation which is done on every timer start is no longer necessary because the granularity levels provide natural batching already. Our extensive testing with various loads did not show any performance degradation vs. the current wheel implementation. This patch does not address the 'fast lookup' issue as we wanted to make sure that there is no regression introduced by the wheel redesign. The optimizations are in follow up patches. This patch contains fixes from Anna-Maria Gleixner and Richard Cochran. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Chris Mason <clm@fb.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: George Spelvin <linux@sciencehorizons.net> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Len Brown <lenb@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160704094342.108621834@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Thomas Gleixner 提交于
Some of the names in the internal implementation of the timer code are not longer correct and others are simply too long to type. Clean it up before we switch the wheel implementation over to the new scheme. No functional change. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Reviewed-by: NFrederic Weisbecker <fweisbec@gmail.com> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Chris Mason <clm@fb.com> Cc: Eric Dumazet <edumazet@google.com> Cc: George Spelvin <linux@sciencehorizons.net> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Len Brown <lenb@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160704094341.948752516@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Thomas Gleixner 提交于
We switched all users to initialize the timers as pinned and call mod_timer(). Remove the now unused timer API function. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Reviewed-by: NFrederic Weisbecker <fweisbec@gmail.com> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Chris Mason <clm@fb.com> Cc: Eric Dumazet <edumazet@google.com> Cc: George Spelvin <linux@sciencehorizons.net> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Len Brown <lenb@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160704094341.706205231@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Thomas Gleixner 提交于
We want to move the timer migration logic from a 'push' to a 'pull' model. Under the current 'push' model pinned timers are handled via a runtime API variant: mod_timer_pinned(). The 'pull' model requires us to store the pinned attribute of a timer in the timer_list structure itself, as a new TIMER_PINNED bit in timer->flags. This flag must be set at initialization time and the timer APIs recognize the flag. This patch: - Implements the new flag and associated new-style initialization methods - makes mod_timer() recognize new-style pinned timers, - and adds some migration helper facility to allow step by step conversion of old-style to new-style pinned timers. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Reviewed-by: NFrederic Weisbecker <fweisbec@gmail.com> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Chris Mason <clm@fb.com> Cc: Eric Dumazet <edumazet@google.com> Cc: George Spelvin <linux@sciencehorizons.net> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Len Brown <lenb@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160704094341.049338558@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
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- 05 7月, 2016 1 次提交
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由 Jisheng Zhang 提交于
This is to avoid the "null" name when we either ~ # cat /sys/devices/system/clockevents/broadcast/current_device (null) or ~ # cat /proc/timer_list ... Tick Device: mode: 1 Broadcast device Clock Event Device: (null) ... Signed-off-by: NJisheng Zhang <jszhang@marvell.com> Cc: linux-arm-kernel@lists.infradead.org Link: http://lkml.kernel.org/r/1467709071-3667-1-git-send-email-jszhang@marvell.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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- 01 7月, 2016 2 次提交
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由 Ingo Molnar 提交于
While reviewing another patch I noticed that kernel/time/tick-sched.c had a charmingly (confusingly, annoyingly) rich set of variants for spelling 'CPU': cpu cpus CPU CPUs per CPU per-CPU per cpu ... sometimes these were mixed even within the same comment block! Compress these variants down to a single consistent set of: CPU CPUs per-CPU Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: linux-kernel@vger.kernel.org Signed-off-by: NIngo Molnar <mingo@kernel.org>
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由 Wei Jiangang 提交于
Signed-off-by: NWei Jiangang <weijg.fnst@cn.fujitsu.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: fenghua.yu@intel.com Link: http://lkml.kernel.org/r/1467175910-2966-2-git-send-email-weijg.fnst@cn.fujitsu.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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