- 06 5月, 2016 13 次提交
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由 Thomas Gleixner 提交于
No need for an extra notifier. We don't need to handle all these states. It's sufficient to kill the timer when the cpu dies. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Acked-by: NPeter Zijlstra <peterz@infradead.org> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160310120025.770528462@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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由 Thomas Gleixner 提交于
No need for an extra notifier. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Acked-by: NPeter Zijlstra <peterz@infradead.org> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160310120025.693720241@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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由 Thomas Gleixner 提交于
Remove the hotplug notifier and make it an explicit state. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Acked-by: NPeter Zijlstra <peterz@infradead.org> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160310120025.502222097@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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由 Thomas Gleixner 提交于
The alleged requirement that the migration notifier has a lower priority than perf is completely undocumented and there is no indication at all that this is true. perf does not even handle the CPU_ONLINE notification and perf really has nothing to do with migration. Move the CPU_ONLINE code into the sched_activate_cpu() state callback. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Acked-by: NPeter Zijlstra <peterz@infradead.org> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160310120025.421743581@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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由 Thomas Gleixner 提交于
It really does not matter when we fold the load for the outgoing cpu. It's almost dead anyway, so there is no harm if we fail to fold the few microseconds which are required for going fully away. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Acked-by: NPeter Zijlstra <peterz@infradead.org> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160310120025.328739226@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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由 Thomas Gleixner 提交于
We can piggy pack that on the SCHED_STARTING state. It's not required before the cpu actually comes online. Name the function proper as it has nothing to do with migration. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Acked-by: NPeter Zijlstra <peterz@infradead.org> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160310120025.248226511@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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由 Peter Zijlstra 提交于
The sync_rcu stuff is specificically for clearing bits in the active mask, such that everybody will observe the bit cleared and will not consider the cleared CPU for load-balancing etc. Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160310120025.169219710@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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由 Thomas Gleixner 提交于
Now that we reduced everything into single notifiers, it's simple to move them into the hotplug state machine space. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Acked-by: NPeter Zijlstra <peterz@infradead.org> Cc: rt@linutronix.de Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
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由 Thomas Gleixner 提交于
This is the last operation on the cpu before vanishing. No point in calling that on CPU_DEAD. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Acked-by: NPeter Zijlstra <peterz@infradead.org> Cc: rt@linutronix.de Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
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由 Thomas Gleixner 提交于
We can maintain the ordering of the scheduler cpu hotplug functionality nicely in one notifer. Get rid of the maze. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Acked-by: NPeter Zijlstra <peterz@infradead.org> Cc: rt@linutronix.de Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
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由 Thomas Gleixner 提交于
Prevent the SMP scheduler related notifiers to be executed before the smp scheduler is initialized and install them early. This is a preparatory change for further consolidation of the hotplug notifier maze. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Acked-by: NPeter Zijlstra <peterz@infradead.org> Cc: rt@linutronix.de Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
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由 Thomas Gleixner 提交于
Start distangling the maze of hotplug notifiers in the scheduler. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Acked-by: NPeter Zijlstra <peterz@infradead.org> Cc: rt@linutronix.de Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
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由 Peter Zijlstra (Intel) 提交于
In order to enable symmetric hotplug, we must mirror the online && !active state of cpu-down on the cpu-up side. However, to retain sanity, limit this state to per-cpu kthreads. Aside from the change to set_cpus_allowed_ptr(), which allow moving the per-cpu kthreads on, the other critical piece is the cpu selection for pinned tasks in select_task_rq(). This avoids dropping into select_fallback_rq(). select_fallback_rq() cannot be allowed to select !active cpus because its used to migrate user tasks away. And we do not want to move user tasks onto cpus that are in transition. Requested-by: NThomas Gleixner <tglx@linutronix.de> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Tested-by: NThomas Gleixner <tglx@linutronix.de> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Cc: Jan H. Schönherr <jschoenh@amazon.de> Cc: Oleg Nesterov <oleg@redhat.com> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160301152303.GV6356@twins.programming.kicks-ass.netSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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- 29 3月, 2016 1 次提交
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由 Frederic Weisbecker 提交于
This patch functionally reverts: 5fd7a09c ("atomic: Export fetch_or()") During the merge Linus observed that the generic version of fetch_or() was messy: " This makes the ugly "fetch_or()" macro that the scheduler used internally a new generic helper, and does a bad job at it. " e23604ed Merge branch 'timers-nohz-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Now that we have introduced atomic_fetch_or(), fetch_or() is only used by the scheduler in order to deal with thread_info flags which type can vary across architectures. Lets confine fetch_or() back to the scheduler so that we encourage future users to use the more robust and well typed atomic_t version instead. While at it, fetch_or() gets robustified, pasting improvements from a previous patch by Ingo Molnar that avoids needless expression re-evaluations in the loop. Reported-by: NLinus Torvalds <torvalds@linux-foundation.org> Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1458830281-4255-4-git-send-email-fweisbec@gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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- 23 3月, 2016 1 次提交
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由 Dmitry Vyukov 提交于
kcov provides code coverage collection for coverage-guided fuzzing (randomized testing). Coverage-guided fuzzing is a testing technique that uses coverage feedback to determine new interesting inputs to a system. A notable user-space example is AFL (http://lcamtuf.coredump.cx/afl/). However, this technique is not widely used for kernel testing due to missing compiler and kernel support. kcov does not aim to collect as much coverage as possible. It aims to collect more or less stable coverage that is function of syscall inputs. To achieve this goal it does not collect coverage in soft/hard interrupts and instrumentation of some inherently non-deterministic or non-interesting parts of kernel is disbled (e.g. scheduler, locking). Currently there is a single coverage collection mode (tracing), but the API anticipates additional collection modes. Initially I also implemented a second mode which exposes coverage in a fixed-size hash table of counters (what Quentin used in his original patch). I've dropped the second mode for simplicity. This patch adds the necessary support on kernel side. The complimentary compiler support was added in gcc revision 231296. We've used this support to build syzkaller system call fuzzer, which has found 90 kernel bugs in just 2 months: https://github.com/google/syzkaller/wiki/Found-Bugs We've also found 30+ bugs in our internal systems with syzkaller. Another (yet unexplored) direction where kcov coverage would greatly help is more traditional "blob mutation". For example, mounting a random blob as a filesystem, or receiving a random blob over wire. Why not gcov. Typical fuzzing loop looks as follows: (1) reset coverage, (2) execute a bit of code, (3) collect coverage, repeat. A typical coverage can be just a dozen of basic blocks (e.g. an invalid input). In such context gcov becomes prohibitively expensive as reset/collect coverage steps depend on total number of basic blocks/edges in program (in case of kernel it is about 2M). Cost of kcov depends only on number of executed basic blocks/edges. On top of that, kernel requires per-thread coverage because there are always background threads and unrelated processes that also produce coverage. With inlined gcov instrumentation per-thread coverage is not possible. kcov exposes kernel PCs and control flow to user-space which is insecure. But debugfs should not be mapped as user accessible. Based on a patch by Quentin Casasnovas. [akpm@linux-foundation.org: make task_struct.kcov_mode have type `enum kcov_mode'] [akpm@linux-foundation.org: unbreak allmodconfig] [akpm@linux-foundation.org: follow x86 Makefile layout standards] Signed-off-by: NDmitry Vyukov <dvyukov@google.com> Reviewed-by: NKees Cook <keescook@chromium.org> Cc: syzkaller <syzkaller@googlegroups.com> Cc: Vegard Nossum <vegard.nossum@oracle.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Tavis Ormandy <taviso@google.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com> Cc: Kostya Serebryany <kcc@google.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Kees Cook <keescook@google.com> Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: David Drysdale <drysdale@google.com> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 21 3月, 2016 5 次提交
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由 Zhao Lei 提交于
- Use for() instead of while() loop in some functions to make the code simpler. - Use this_cpu_ptr() instead of per_cpu_ptr() to make the code cleaner and a bit faster. Suggested-by: NPeter Zijlstra <peterz@infradead.org> Signed-off-by: NZhao Lei <zhaolei@cn.fujitsu.com> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Tejun Heo <htejun@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/d8a7ef9592f55224630cb26dea239f05b6398a4e.1458187654.git.zhaolei@cn.fujitsu.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Dongsheng Yang 提交于
The name of the 'reset' parameter to cpuusage_write() is quite confusing, because the only valid value we allow is '0', so !reset is actually the case that resets ... Rename it to 'val' and explain it in a comment that we only allow 0. Signed-off-by: NDongsheng Yang <yangds.fnst@cn.fujitsu.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: cgroups@vger.kernel.org Cc: tj@kernel.org Link: http://lkml.kernel.org/r/1450696483-2864-1-git-send-email-yangds.fnst@cn.fujitsu.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Matt Fleming 提交于
It's not entirely obvious how the main loop in select_idle_sibling() works on first glance. Sprinkle a few comments to explain the design and intention behind the loop based on some conversations with Mike and Peter. Signed-off-by: NMatt Fleming <matt@codeblueprint.co.uk> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.com> Cc: Mike Galbraith <mgalbraith@suse.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1457535548-15329-1-git-send-email-matt@codeblueprint.co.ukSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Peter Zijlstra 提交于
Pavan reported that in the presence of very light tasks (or cgroups) the placement of migrated tasks can cause severe fairness issues. The problem is that enqueue_entity() places the task before it updates time, thereby it can place the task far in the past (remember that light tasks will shoot virtual time forward at a high speed, so in relation to the pre-existing light task, we can land far in the past). This is done because update_curr() needs the current task, and we might be placing the current task. The obvious solution is to differentiate between the current and any other task; placing the current before we update time, and placing any other task after, such that !curr tasks end up at the current moment in time, and not in the past. Reported-by: NPavan Kondeti <pkondeti@codeaurora.org> Tested-by: NPavan Kondeti <pkondeti@codeaurora.org> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Ben Segall <bsegall@google.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matt Fleming <matt@codeblueprint.co.uk> Cc: Mike Galbraith <umgwanakikbuti@gmail.com> Cc: Morten Rasmussen <morten.rasmussen@arm.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: byungchul.park@lge.com Link: http://lkml.kernel.org/r/20160309120403.GK6344@twins.programming.kicks-ass.netSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Peter Zijlstra 提交于
The CPU controller hasn't kept up with the various changes in the whole cgroup initialization / destruction sequence, and commit: 2e91fa7f ("cgroup: keep zombies associated with their original cgroups") caused it to explode. The reason for this is that zombies do not inhibit css_offline() from being called, but do stall css_released(). Now we tear down the cfs_rq structures on css_offline() but zombies can run after that, leading to use-after-free issues. The solution is to move the tear-down to css_released(), which guarantees nobody (including no zombies) is still using our cgroup. Furthermore, a few simple cleanups are possible too. There doesn't appear to be any point to us using css_online() (anymore?) so fold that in css_alloc(). And since cgroup code guarantees an RCU grace period between css_released() and css_free() we can forgo using call_rcu() and free the stuff immediately. Suggested-by: NTejun Heo <tj@kernel.org> Reported-by: NKazuki Yamaguchi <k@rhe.jp> Reported-by: NNiklas Cassel <niklas.cassel@axis.com> Tested-by: NNiklas Cassel <niklas.cassel@axis.com> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Acked-by: NTejun Heo <tj@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: 2e91fa7f ("cgroup: keep zombies associated with their original cgroups") Link: http://lkml.kernel.org/r/20160316152245.GY6344@twins.programming.kicks-ass.netSigned-off-by: NIngo Molnar <mingo@kernel.org>
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- 11 3月, 2016 1 次提交
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由 Rafael J. Wysocki 提交于
Create cpufreq.c under kernel/sched/ and move the cpufreq code related to the scheduler to that file and to sched.h. Redefine cpufreq_update_util() as a static inline function to avoid function calls at its call sites in the scheduler code (as suggested by Peter Zijlstra). Also move the definition of struct update_util_data and declaration of cpufreq_set_update_util_data() from include/linux/cpufreq.h to include/linux/sched.h. Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
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- 10 3月, 2016 1 次提交
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由 Mark Rutland 提交于
Functions which the compiler has instrumented for KASAN place poison on the stack shadow upon entry and remove this poision prior to returning. In the case of CPU hotplug, CPUs exit the kernel a number of levels deep in C code. Any instrumented functions on this critical path will leave portions of the stack shadow poisoned. When a CPU is subsequently brought back into the kernel via a different path, depending on stackframe, layout calls to instrumented functions may hit this stale poison, resulting in (spurious) KASAN splats to the console. To avoid this, clear any stale poison from the idle thread for a CPU prior to bringing a CPU online. Signed-off-by: NMark Rutland <mark.rutland@arm.com> Acked-by: NCatalin Marinas <catalin.marinas@arm.com> Reviewed-by: NAndrey Ryabinin <aryabinin@virtuozzo.com> Reviewed-by: NIngo Molnar <mingo@kernel.org> Cc: Alexander Potapenko <glider@google.com> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 09 3月, 2016 1 次提交
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由 Rafael J. Wysocki 提交于
Introduce a mechanism by which parts of the cpufreq subsystem ("setpolicy" drivers or the core) can register callbacks to be executed from cpufreq_update_util() which is invoked by the scheduler's update_load_avg() on CPU utilization changes. This allows the "setpolicy" drivers to dispense with their timers and do all of the computations they need and frequency/voltage adjustments in the update_load_avg() code path, among other things. The update_load_avg() changes were suggested by Peter Zijlstra. Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: NViresh Kumar <viresh.kumar@linaro.org> Acked-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Acked-by: NIngo Molnar <mingo@kernel.org>
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- 08 3月, 2016 2 次提交
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由 Chris Friesen 提交于
The callers of steal_account_process_tick() expect it to return whether a jiffy should be considered stolen or not. Currently the return value of steal_account_process_tick() is in units of cputime, which vary between either jiffies or nsecs depending on CONFIG_VIRT_CPU_ACCOUNTING_GEN. If cputime has nsecs granularity and there is a tiny amount of stolen time (a few nsecs, say) then we will consider the entire tick stolen and will not account the tick on user/system/idle, causing /proc/stats to show invalid data. The fix is to change steal_account_process_tick() to accumulate the stolen time and only account it once it's worth a jiffy. (Thanks to Frederic Weisbecker for suggestions to fix a bug in my first version of the patch.) Signed-off-by: NChris Friesen <chris.friesen@windriver.com> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: NThomas Gleixner <tglx@linutronix.de> Cc: <stable@vger.kernel.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/56DBBDB8.40305@mail.usask.caSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Luca Abeni 提交于
The dl_new field of struct sched_dl_entity is currently used to identify new deadline tasks, so that their deadline and runtime can be properly initialised. However, these tasks can be easily identified by checking if their deadline is smaller than the current time when they switch to SCHED_DEADLINE. So, dl_new can be removed by introducing this check in switched_to_dl(); this allows to simplify the SCHED_DEADLINE code. Signed-off-by: NLuca Abeni <luca.abeni@unitn.it> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Juri Lelli <juri.lelli@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1457350024-7825-2-git-send-email-luca.abeni@unitn.itSigned-off-by: NIngo Molnar <mingo@kernel.org>
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- 05 3月, 2016 1 次提交
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由 Thomas Gleixner 提交于
On CPU hotplug the steal time accounting can keep a stale rq->prev_steal_time value over CPU down and up. So after the CPU comes up again the delta calculation in steal_account_process_tick() wreckages itself due to the unsigned math: u64 steal = paravirt_steal_clock(smp_processor_id()); steal -= this_rq()->prev_steal_time; So if steal is smaller than rq->prev_steal_time we end up with an insane large value which then gets added to rq->prev_steal_time, resulting in a permanent wreckage of the accounting. As a consequence the per CPU stats in /proc/stat become stale. Nice trick to tell the world how idle the system is (100%) while the CPU is 100% busy running tasks. Though we prefer realistic numbers. None of the accounting values which use a previous value to account for fractions is reset at CPU hotplug time. update_rq_clock_task() has a sanity check for prev_irq_time and prev_steal_time_rq, but that sanity check solely deals with clock warps and limits the /proc/stat visible wreckage. The prev_time values are still wrong. Solution is simple: Reset rq->prev_*_time when the CPU is plugged in again. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Acked-by: NRik van Riel <riel@redhat.com> Cc: <stable@vger.kernel.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Glauber Costa <glommer@parallels.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Fixes: commit 095c0aa8 "sched: adjust scheduler cpu power for stolen time" Fixes: commit aa483808 "sched: Remove irq time from available CPU power" Fixes: commit e6e6685a "KVM guest: Steal time accounting" Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1603041539490.3686@nanosSigned-off-by: NIngo Molnar <mingo@kernel.org>
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- 02 3月, 2016 8 次提交
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由 Frederic Weisbecker 提交于
Instead of checking sched_clock_stable from the nohz subsystem to verify its tick dependency, migrate it to the new mask in order to include it to the all-in-one check. Reviewed-by: NChris Metcalf <cmetcalf@ezchip.com> Cc: Christoph Lameter <cl@linux.com> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
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由 Frederic Weisbecker 提交于
Instead of providing asynchronous checks for the nohz subsystem to verify sched tick dependency, migrate sched to the new mask. Everytime a task is enqueued or dequeued, we evaluate the state of the tick dependency on top of the policy of the tasks in the runqueue, by order of priority: SCHED_DEADLINE: Need the tick in order to periodically check for runtime SCHED_FIFO : Don't need the tick (no round-robin) SCHED_RR : Need the tick if more than 1 task of the same priority for round robin (simplified with checking if more than one SCHED_RR task no matter what priority). SCHED_NORMAL : Need the tick if more than 1 task for round-robin. We could optimize that further with one flag per sched policy on the tick dependency mask and perform only the checks relevant to the policy concerned by an enqueue/dequeue operation. Since the checks aren't based on the current task anymore, we could get rid of the task switch hook but it's still needed for posix cpu timers. Reviewed-by: NChris Metcalf <cmetcalf@ezchip.com> Cc: Christoph Lameter <cl@linux.com> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
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由 Frederic Weisbecker 提交于
In order to evaluate the scheduler tick dependency without probing context switches, we need to know how much SCHED_RR and SCHED_FIFO tasks are enqueued as those policies don't have the same preemption requirements. To prepare for that, let's account SCHED_RR tasks, we'll be able to deduce SCHED_FIFO tasks as well from it and the total RT tasks in the runqueue. Reviewed-by: NChris Metcalf <cmetcalf@ezchip.com> Cc: Christoph Lameter <cl@linux.com> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
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由 Alexander Gordeev 提交于
Given that wq_worker_sleeping() could only be called for a CPU it is running on, we do not need passing a CPU ID as an argument. Suggested-by: NOleg Nesterov <oleg@redhat.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: NAlexander Gordeev <agordeev@redhat.com> Signed-off-by: NTejun Heo <tj@kernel.org>
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由 Thomas Gleixner 提交于
Make the RCU CPU_DYING_IDLE callback an explicit function call, so it gets invoked at the proper place. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Cc: linux-arch@vger.kernel.org Cc: Rik van Riel <riel@redhat.com> Cc: Rafael Wysocki <rafael.j.wysocki@intel.com> Cc: "Srivatsa S. Bhat" <srivatsa@mit.edu> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Paul McKenney <paulmck@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul Turner <pjt@google.com> Link: http://lkml.kernel.org/r/20160226182341.870167933@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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由 Thomas Gleixner 提交于
Kill the busy spinning on the control side and just wait for the hotplugged cpu to tell that it reached the dead state. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Cc: linux-arch@vger.kernel.org Cc: Rik van Riel <riel@redhat.com> Cc: Rafael Wysocki <rafael.j.wysocki@intel.com> Cc: "Srivatsa S. Bhat" <srivatsa@mit.edu> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Paul McKenney <paulmck@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul Turner <pjt@google.com> Link: http://lkml.kernel.org/r/20160226182341.776157858@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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由 Thomas Gleixner 提交于
Let the upcoming cpu kick the hotplug thread and let itself complete the bringup. That way the controll side can just wait for the completion or later when we made the hotplug machinery async not care at all. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Cc: linux-arch@vger.kernel.org Cc: Rik van Riel <riel@redhat.com> Cc: Rafael Wysocki <rafael.j.wysocki@intel.com> Cc: "Srivatsa S. Bhat" <srivatsa@mit.edu> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Paul McKenney <paulmck@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul Turner <pjt@google.com> Link: http://lkml.kernel.org/r/20160226182341.697655464@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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由 Thomas Gleixner 提交于
Move the scheduler cpu online notifier part to the hotplug core. This is anyway the highest priority callback and we need that functionality right now for the next changes. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Cc: linux-arch@vger.kernel.org Cc: Rik van Riel <riel@redhat.com> Cc: Rafael Wysocki <rafael.j.wysocki@intel.com> Cc: "Srivatsa S. Bhat" <srivatsa@mit.edu> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Paul McKenney <paulmck@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul Turner <pjt@google.com> Link: http://lkml.kernel.org/r/20160226182341.200791046@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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- 29 2月, 2016 6 次提交
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由 Peter Zijlstra 提交于
if (A || B) { } else if (A && !B) { } If A we'll take the first branch, if !A we will not satisfy the second. Therefore the second branch will never be taken. Reported-by: Nluca abeni <luca.abeni@unitn.it> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Acked-by: NJuri Lelli <juri.lelli@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20160225140149.GK6357@twins.programming.kicks-ass.netSigned-off-by: NIngo Molnar <mingo@kernel.org>
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The preempt_disable() invokes preempt_count_add() which saves the caller in ->preempt_disable_ip. It uses CALLER_ADDR1 which does not look for its caller but for the parent of the caller. Which means we get the correct caller for something like spin_lock() unless the architectures inlines those invocations. It is always wrong for preempt_disable() or local_bh_disable(). This patch makes the function get_lock_parent_ip() which tries CALLER_ADDR0,1,2 if the former is a locking function. This seems to record the preempt_disable() caller properly for preempt_disable() itself as well as for get_cpu_var() or local_bh_disable(). Steven asked for the get_parent_ip() -> get_lock_parent_ip() rename. Signed-off-by: NSebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20160226135456.GB18244@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Rik van Riel 提交于
When profiling syscall overhead on nohz-full kernels, after removing __acct_update_integrals() from the profile, native_sched_clock() remains as the top CPU user. This can be reduced by moving VIRT_CPU_ACCOUNTING_GEN to jiffy granularity. This will reduce timing accuracy on nohz_full CPUs to jiffy based sampling, just like on normal CPUs. It results in totally removing native_sched_clock from the profile, and significantly speeding up the syscall entry and exit path, as well as irq entry and exit, and KVM guest entry & exit. Additionally, only call the more expensive functions (and advance the seqlock) when jiffies actually changed. This code relies on another CPU advancing jiffies when the system is busy. On a nohz_full system, this is done by a housekeeping CPU. A microbenchmark calling an invalid syscall number 10 million times in a row speeds up an additional 30% over the numbers with just the previous patches, for a total speedup of about 40% over 4.4 and 4.5-rc1. Run times for the microbenchmark: 4.4 3.8 seconds 4.5-rc1 3.7 seconds 4.5-rc1 + first patch 3.3 seconds 4.5-rc1 + first 3 patches 3.1 seconds 4.5-rc1 + all patches 2.3 seconds A non-NOHZ_FULL cpu (not the housekeeping CPU): all kernels 1.86 seconds Signed-off-by: NRik van Riel <riel@redhat.com> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: NThomas Gleixner <tglx@linutronix.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: clark@redhat.com Cc: eric.dumazet@gmail.com Cc: fweisbec@gmail.com Cc: luto@amacapital.net Link: http://lkml.kernel.org/r/1455152907-18495-5-git-send-email-riel@redhat.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Steven Rostedt 提交于
I've been debugging why deadline tasks can cause the RT scheduler to throttle, even when the deadline tasks are only taking up 50% of the CPU and RT tasks are not even using 1% of the CPU. Here's what I found. In order to keep a CPU from being hogged by RT tasks, the deadline scheduler adds its run time (delta_exec) to the rt_time of the RT bandwidth. That way, if the two use more than 95% of the CPU within one second (default settings), the RT tasks are throttled to allow non RT tasks to run. Although the deadline tasks add their run time to the RT bandwidth, it lets the RT tasks do the accounting. This is where the problem lies. If a deadline task runs for a bit, and no RT tasks are running, then it will continually add to the RT rt_time that is used to calculate how much CPU the RT tasks use. But no RT period is in play, and this accumulation of the runtime never gets reset. When an RT task finally gets to run, and the watchdog goes off, it can see that the RT task has used more than it should of, because the deadline task added all this runtime to its rt_time. Then the RT task that just woke up gets throttled for no good reason. I also noticed that when an RT task is queued, it starts the timer to account for overload and such. But that timer goes off one period later, which may be too late and the extra rt_time will trigger a throttle. This is a quick work around to the problem. When a new RT task is queued, the bandwidth timer is set to go off immediately. Then the timer can clear out the extra time added to the rt_time while there was no RT task running. This stops my tests from triggering the throttle, and it will still throttle if an RT task runs too much, even while a deadline task is running. A better solution may be to subtract the bandwidth that the deadline task uses from the rt_runtime, and add it back when its finished. Then there wont be a need for runtime tracking of the time used by deadline tasks. I may play with that solution tomorrow. Signed-off-by: NSteven Rostedt <rostedt@goodmis.org> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: <juri.lelli@gmail.com> Cc: <williams@redhat.com> Cc: Clark Williams Cc: Daniel Bristot de Oliveira <bristot@redhat.com> Cc: John Kacur <jkacur@redhat.com> Cc: Juri Lelli Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20160216183746.349ec98b@gandalf.local.homeSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Steven Rostedt (Red Hat) 提交于
Playing with SCHED_DEADLINE and cpusets, I found that I was unable to create new SCHED_DEADLINE tasks, with the error of EBUSY as if the bandwidth was already used up. I then realized there wa no way to see what bandwidth is used by the runqueues to debug the issue. By adding the dl_bw->bw and dl_bw->total_bw to the output of the deadline info in /proc/sched_debug, this allows us to see what bandwidth has been reserved and where a problem may exist. For example, before the issue we see the ratio of the bandwidth: # cat /proc/sys/kernel/sched_rt_runtime_us 950000 # cat /proc/sys/kernel/sched_rt_period_us 1000000 # grep dl /proc/sched_debug dl_rq[0]: .dl_nr_running : 0 .dl_bw->bw : 996147 .dl_bw->total_bw : 0 dl_rq[1]: .dl_nr_running : 0 .dl_bw->bw : 996147 .dl_bw->total_bw : 0 dl_rq[2]: .dl_nr_running : 0 .dl_bw->bw : 996147 .dl_bw->total_bw : 0 dl_rq[3]: .dl_nr_running : 0 .dl_bw->bw : 996147 .dl_bw->total_bw : 0 dl_rq[4]: .dl_nr_running : 0 .dl_bw->bw : 996147 .dl_bw->total_bw : 0 dl_rq[5]: .dl_nr_running : 0 .dl_bw->bw : 996147 .dl_bw->total_bw : 0 dl_rq[6]: .dl_nr_running : 0 .dl_bw->bw : 996147 .dl_bw->total_bw : 0 dl_rq[7]: .dl_nr_running : 0 .dl_bw->bw : 996147 .dl_bw->total_bw : 0 Note: (950000 / 1000000) << 20 == 996147 After I played with cpusets and hit the issue, the result is now: # grep dl /proc/sched_debug dl_rq[0]: .dl_nr_running : 0 .dl_bw->bw : 996147 .dl_bw->total_bw : -104857 dl_rq[1]: .dl_nr_running : 0 .dl_bw->bw : 996147 .dl_bw->total_bw : 104857 dl_rq[2]: .dl_nr_running : 0 .dl_bw->bw : 996147 .dl_bw->total_bw : 104857 dl_rq[3]: .dl_nr_running : 0 .dl_bw->bw : 996147 .dl_bw->total_bw : 104857 dl_rq[4]: .dl_nr_running : 0 .dl_bw->bw : 996147 .dl_bw->total_bw : -104857 dl_rq[5]: .dl_nr_running : 0 .dl_bw->bw : 996147 .dl_bw->total_bw : -104857 dl_rq[6]: .dl_nr_running : 0 .dl_bw->bw : 996147 .dl_bw->total_bw : -104857 dl_rq[7]: .dl_nr_running : 0 .dl_bw->bw : 996147 .dl_bw->total_bw : -104857 This shows that there is definitely a problem as we should never have a negative total bandwidth. Signed-off-by: NSteven Rostedt <rostedt@goodmis.org> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Clark Williams <williams@redhat.com> Cc: Juri Lelli <juri.lelli@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20160222212825.756849091@goodmis.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Steven Rostedt (Red Hat) 提交于
The sched_domain_sysctl setup is only enabled when SCHED_DEBUG is configured. As debug.c is only compiled when SCHED_DEBUG is configured as well, move the setup of sched_domain_sysctl into that file. Note, the (un)register_sched_domain_sysctl() functions had to be changed from static to allow access to them from core.c. Signed-off-by: NSteven Rostedt <rostedt@goodmis.org> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Clark Williams <williams@redhat.com> Cc: Juri Lelli <juri.lelli@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20160222212825.599278093@goodmis.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
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