- 13 1月, 2014 7 次提交
-
-
由 Dario Faggioli 提交于
In order of deadline scheduling to be effective and useful, it is important that some method of having the allocation of the available CPU bandwidth to tasks and task groups under control. This is usually called "admission control" and if it is not performed at all, no guarantee can be given on the actual scheduling of the -deadline tasks. Since when RT-throttling has been introduced each task group have a bandwidth associated to itself, calculated as a certain amount of runtime over a period. Moreover, to make it possible to manipulate such bandwidth, readable/writable controls have been added to both procfs (for system wide settings) and cgroupfs (for per-group settings). Therefore, the same interface is being used for controlling the bandwidth distrubution to -deadline tasks and task groups, i.e., new controls but with similar names, equivalent meaning and with the same usage paradigm are added. However, more discussion is needed in order to figure out how we want to manage SCHED_DEADLINE bandwidth at the task group level. Therefore, this patch adds a less sophisticated, but actually very sensible, mechanism to ensure that a certain utilization cap is not overcome per each root_domain (the single rq for !SMP configurations). Another main difference between deadline bandwidth management and RT-throttling is that -deadline tasks have bandwidth on their own (while -rt ones doesn't!), and thus we don't need an higher level throttling mechanism to enforce the desired bandwidth. This patch, therefore: - adds system wide deadline bandwidth management by means of: * /proc/sys/kernel/sched_dl_runtime_us, * /proc/sys/kernel/sched_dl_period_us, that determine (i.e., runtime / period) the total bandwidth available on each CPU of each root_domain for -deadline tasks; - couples the RT and deadline bandwidth management, i.e., enforces that the sum of how much bandwidth is being devoted to -rt -deadline tasks to stay below 100%. This means that, for a root_domain comprising M CPUs, -deadline tasks can be created until the sum of their bandwidths stay below: M * (sched_dl_runtime_us / sched_dl_period_us) It is also possible to disable this bandwidth management logic, and be thus free of oversubscribing the system up to any arbitrary level. Signed-off-by: NDario Faggioli <raistlin@linux.it> Signed-off-by: NJuri Lelli <juri.lelli@gmail.com> Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1383831828-15501-12-git-send-email-juri.lelli@gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
-
由 Dario Faggioli 提交于
Some method to deal with rt-mutexes and make sched_dl interact with the current PI-coded is needed, raising all but trivial issues, that needs (according to us) to be solved with some restructuring of the pi-code (i.e., going toward a proxy execution-ish implementation). This is under development, in the meanwhile, as a temporary solution, what this commits does is: - ensure a pi-lock owner with waiters is never throttled down. Instead, when it runs out of runtime, it immediately gets replenished and it's deadline is postponed; - the scheduling parameters (relative deadline and default runtime) used for that replenishments --during the whole period it holds the pi-lock-- are the ones of the waiting task with earliest deadline. Acting this way, we provide some kind of boosting to the lock-owner, still by using the existing (actually, slightly modified by the previous commit) pi-architecture. We would stress the fact that this is only a surely needed, all but clean solution to the problem. In the end it's only a way to re-start discussion within the community. So, as always, comments, ideas, rants, etc.. are welcome! :-) Signed-off-by: NDario Faggioli <raistlin@linux.it> Signed-off-by: NJuri Lelli <juri.lelli@gmail.com> [ Added !RT_MUTEXES build fix. ] Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1383831828-15501-11-git-send-email-juri.lelli@gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
-
由 Peter Zijlstra 提交于
Turn the pi-chains from plist to rb-tree, in the rt_mutex code, and provide a proper comparison function for -deadline and -priority tasks. This is done mainly because: - classical prio field of the plist is just an int, which might not be enough for representing a deadline; - manipulating such a list would become O(nr_deadline_tasks), which might be to much, as the number of -deadline task increases. Therefore, an rb-tree is used, and tasks are queued in it according to the following logic: - among two -priority (i.e., SCHED_BATCH/OTHER/RR/FIFO) tasks, the one with the higher (lower, actually!) prio wins; - among a -priority and a -deadline task, the latter always wins; - among two -deadline tasks, the one with the earliest deadline wins. Queueing and dequeueing functions are changed accordingly, for both the list of a task's pi-waiters and the list of tasks blocked on a pi-lock. Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Signed-off-by: NDario Faggioli <raistlin@linux.it> Signed-off-by: NJuri Lelli <juri.lelli@gmail.com> Signed-off-again-by: NPeter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1383831828-15501-10-git-send-email-juri.lelli@gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
-
由 Harald Gustafsson 提交于
Make it possible to specify a period (different or equal than deadline) for -deadline tasks. Relative deadlines (D_i) are used on task arrivals to generate new scheduling (absolute) deadlines as "d = t + D_i", and periods (P_i) to postpone the scheduling deadlines as "d = d + P_i" when the budget is zero. This is in general useful to model (and schedule) tasks that have slow activation rates (long periods), but have to be scheduled soon once activated (short deadlines). Signed-off-by: NHarald Gustafsson <harald.gustafsson@ericsson.com> Signed-off-by: NDario Faggioli <raistlin@linux.it> Signed-off-by: NJuri Lelli <juri.lelli@gmail.com> Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1383831828-15501-7-git-send-email-juri.lelli@gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
-
由 Juri Lelli 提交于
Introduces data structures relevant for implementing dynamic migration of -deadline tasks and the logic for checking if runqueues are overloaded with -deadline tasks and for choosing where a task should migrate, when it is the case. Adds also dynamic migrations to SCHED_DEADLINE, so that tasks can be moved among CPUs when necessary. It is also possible to bind a task to a (set of) CPU(s), thus restricting its capability of migrating, or forbidding migrations at all. The very same approach used in sched_rt is utilised: - -deadline tasks are kept into CPU-specific runqueues, - -deadline tasks are migrated among runqueues to achieve the following: * on an M-CPU system the M earliest deadline ready tasks are always running; * affinity/cpusets settings of all the -deadline tasks is always respected. Therefore, this very special form of "load balancing" is done with an active method, i.e., the scheduler pushes or pulls tasks between runqueues when they are woken up and/or (de)scheduled. IOW, every time a preemption occurs, the descheduled task might be sent to some other CPU (depending on its deadline) to continue executing (push). On the other hand, every time a CPU becomes idle, it might pull the second earliest deadline ready task from some other CPU. To enforce this, a pull operation is always attempted before taking any scheduling decision (pre_schedule()), as well as a push one after each scheduling decision (post_schedule()). In addition, when a task arrives or wakes up, the best CPU where to resume it is selected taking into account its affinity mask, the system topology, but also its deadline. E.g., from the scheduling point of view, the best CPU where to wake up (and also where to push) a task is the one which is running the task with the latest deadline among the M executing ones. In order to facilitate these decisions, per-runqueue "caching" of the deadlines of the currently running and of the first ready task is used. Queued but not running tasks are also parked in another rb-tree to speed-up pushes. Signed-off-by: NJuri Lelli <juri.lelli@gmail.com> Signed-off-by: NDario Faggioli <raistlin@linux.it> Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1383831828-15501-5-git-send-email-juri.lelli@gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
-
由 Dario Faggioli 提交于
Introduces the data structures, constants and symbols needed for SCHED_DEADLINE implementation. Core data structure of SCHED_DEADLINE are defined, along with their initializers. Hooks for checking if a task belong to the new policy are also added where they are needed. Adds a scheduling class, in sched/dl.c and a new policy called SCHED_DEADLINE. It is an implementation of the Earliest Deadline First (EDF) scheduling algorithm, augmented with a mechanism (called Constant Bandwidth Server, CBS) that makes it possible to isolate the behaviour of tasks between each other. The typical -deadline task will be made up of a computation phase (instance) which is activated on a periodic or sporadic fashion. The expected (maximum) duration of such computation is called the task's runtime; the time interval by which each instance need to be completed is called the task's relative deadline. The task's absolute deadline is dynamically calculated as the time instant a task (better, an instance) activates plus the relative deadline. The EDF algorithms selects the task with the smallest absolute deadline as the one to be executed first, while the CBS ensures each task to run for at most its runtime every (relative) deadline length time interval, avoiding any interference between different tasks (bandwidth isolation). Thanks to this feature, also tasks that do not strictly comply with the computational model sketched above can effectively use the new policy. To summarize, this patch: - introduces the data structures, constants and symbols needed; - implements the core logic of the scheduling algorithm in the new scheduling class file; - provides all the glue code between the new scheduling class and the core scheduler and refines the interactions between sched/dl and the other existing scheduling classes. Signed-off-by: NDario Faggioli <raistlin@linux.it> Signed-off-by: NMichael Trimarchi <michael@amarulasolutions.com> Signed-off-by: NFabio Checconi <fchecconi@gmail.com> Signed-off-by: NJuri Lelli <juri.lelli@gmail.com> Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1383831828-15501-4-git-send-email-juri.lelli@gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
-
由 Dario Faggioli 提交于
Add the syscalls needed for supporting scheduling algorithms with extended scheduling parameters (e.g., SCHED_DEADLINE). In general, it makes possible to specify a periodic/sporadic task, that executes for a given amount of runtime at each instance, and is scheduled according to the urgency of their own timing constraints, i.e.: - a (maximum/typical) instance execution time, - a minimum interval between consecutive instances, - a time constraint by which each instance must be completed. Thus, both the data structure that holds the scheduling parameters of the tasks and the system calls dealing with it must be extended. Unfortunately, modifying the existing struct sched_param would break the ABI and result in potentially serious compatibility issues with legacy binaries. For these reasons, this patch: - defines the new struct sched_attr, containing all the fields that are necessary for specifying a task in the computational model described above; - defines and implements the new scheduling related syscalls that manipulate it, i.e., sched_setattr() and sched_getattr(). Syscalls are introduced for x86 (32 and 64 bits) and ARM only, as a proof of concept and for developing and testing purposes. Making them available on other architectures is straightforward. Since no "user" for these new parameters is introduced in this patch, the implementation of the new system calls is just identical to their already existing counterpart. Future patches that implement scheduling policies able to exploit the new data structure must also take care of modifying the sched_*attr() calls accordingly with their own purposes. Signed-off-by: NDario Faggioli <raistlin@linux.it> [ Rewrote to use sched_attr. ] Signed-off-by: NJuri Lelli <juri.lelli@gmail.com> [ Removed sched_setscheduler2() for now. ] Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1383831828-15501-3-git-send-email-juri.lelli@gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
-
- 11 12月, 2013 2 次提交
-
-
由 Peter Zijlstra 提交于
Christian suffers from a bad BIOS that wrecks his i5's TSC sync. This results in him occasionally seeing time going backwards - which crashes the scheduler ... Most of our time accounting can actually handle that except the most common one; the tick time update of sched_fair. There is a further problem with that code; previously we assumed that because we get a tick every TICK_NSEC our time delta could never exceed 32bits and math was simpler. However, ever since Frederic managed to get NO_HZ_FULL merged; this is no longer the case since now a task can run for a long time indeed without getting a tick. It only takes about ~4.2 seconds to overflow our u32 in nanoseconds. This means we not only need to better deal with time going backwards; but also means we need to be able to deal with large deltas. This patch reworks the entire code and uses mul_u64_u32_shr() as proposed by Andy a long while ago. We express our virtual time scale factor in a u32 multiplier and shift right and the 32bit mul_u64_u32_shr() implementation reduces to a single 32x32->64 multiply if the time delta is still short (common case). For 64bit a 64x64->128 multiply can be used if ARCH_SUPPORTS_INT128. Reported-and-Tested-by: NChristian Engelmayer <cengelma@gmx.at> Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Cc: fweisbec@gmail.com Cc: Paul Turner <pjt@google.com> Cc: Stanislaw Gruszka <sgruszka@redhat.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/20131118172706.GI3866@twins.programming.kicks-ass.netSigned-off-by: NIngo Molnar <mingo@kernel.org>
-
由 Peter Zijlstra 提交于
While hunting a preemption issue with Alexander, Ben noticed that the currently generic PREEMPT_NEED_RESCHED stuff is horribly broken for load-store architectures. We currently rely on the IPI to fold TIF_NEED_RESCHED into PREEMPT_NEED_RESCHED, but when this IPI lands while we already have a load for the preempt-count but before the store, the store will erase the PREEMPT_NEED_RESCHED change. The current preempt-count only works on load-store archs because interrupts are assumed to be completely balanced wrt their preempt_count fiddling; the previous preempt_count load will match the preempt_count state after the interrupt and therefore nothing gets lost. This patch removes the PREEMPT_NEED_RESCHED usage from generic code and pushes it into x86 arch code; the generic code goes back to relying on TIF_NEED_RESCHED. Boot tested on x86_64 and compile tested on ppc64. Reported-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org> Reported-and-Tested-by: NAlexander Graf <agraf@suse.de> Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/20131128132641.GP10022@twins.programming.kicks-ass.netSigned-off-by: NIngo Molnar <mingo@kernel.org>
-
- 27 11月, 2013 1 次提交
-
-
由 Oleg Nesterov 提交于
task_is_dead() has no users since commit 43e13cc1 ("cred: remove task_is_dead() from __task_cred() validation"), and nobody except exit.c should rely on ->exit_state (we still have the users which should be changed). Signed-off-by: NOleg Nesterov <oleg@redhat.com> Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Cc: David Laight <David.Laight@ACULAB.COM> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/20131113143614.GA10547@redhat.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
-
- 20 11月, 2013 1 次提交
-
-
由 Alex Shi 提交于
The 'u64 last_update' variable isn't used now, remove it to save a bit of space. Signed-off-by: NAlex Shi <alex.shi@linaro.org> Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Cc: Morten.Rasmussen@arm.com Cc: linaro-kernel@lists.linaro.org Link: http://lkml.kernel.org/r/1384852912-24791-1-git-send-email-alex.shi@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
-
- 14 11月, 2013 1 次提交
-
-
由 Thomas Gleixner 提交于
No point in having this bit defined by architecture. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Acked-by: NPeter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20130917183629.090698799@linutronix.de
-
- 13 11月, 2013 2 次提交
-
-
由 Kees Cook 提交于
The get_dumpable() return value is not boolean. Most users of the function actually want to be testing for non-SUID_DUMP_USER(1) rather than SUID_DUMP_DISABLE(0). The SUID_DUMP_ROOT(2) is also considered a protected state. Almost all places did this correctly, excepting the two places fixed in this patch. Wrong logic: if (dumpable == SUID_DUMP_DISABLE) { /* be protective */ } or if (dumpable == 0) { /* be protective */ } or if (!dumpable) { /* be protective */ } Correct logic: if (dumpable != SUID_DUMP_USER) { /* be protective */ } or if (dumpable != 1) { /* be protective */ } Without this patch, if the system had set the sysctl fs/suid_dumpable=2, a user was able to ptrace attach to processes that had dropped privileges to that user. (This may have been partially mitigated if Yama was enabled.) The macros have been moved into the file that declares get/set_dumpable(), which means things like the ia64 code can see them too. CVE-2013-2929 Reported-by: NVasily Kulikov <segoon@openwall.com> Signed-off-by: NKees Cook <keescook@chromium.org> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: <stable@vger.kernel.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
由 Vineet Gupta 提交于
fpu_counter in task_struct was used only by sh/x86. Both of these now carry it in ARCH specific thread_struct, hence this can now be removed from generic task_struct, shrinking it slightly for other arches. Signed-off-by: NVineet Gupta <vgupta@synopsys.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Paul Mundt <paul.mundt@gmail.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
- 06 11月, 2013 1 次提交
-
-
由 Marcelo Tosatti 提交于
In certain occasions it is possible for a hung task detector positive to be false: continuation from a paused VM, for example. Add a method to reset detection, similar as is done with other kernel watchdogs. Acked-by: NDon Zickus <dzickus@redhat.com> Acked-by: NPaolo Bonzini <pbonzini@redhat.com> Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com> Signed-off-by: NGleb Natapov <gleb@redhat.com>
-
- 17 10月, 2013 1 次提交
-
-
由 Johannes Weiner 提交于
Commit 3812c8c8 ("mm: memcg: do not trap chargers with full callstack on OOM") assumed that only a few places that can trigger a memcg OOM situation do not return VM_FAULT_OOM, like optional page cache readahead. But there are many more and it's impractical to annotate them all. First of all, we don't want to invoke the OOM killer when the failed allocation is gracefully handled, so defer the actual kill to the end of the fault handling as well. This simplifies the code quite a bit for added bonus. Second, since a failed allocation might not be the abrupt end of the fault, the memcg OOM handler needs to be re-entrant until the fault finishes for subsequent allocation attempts. If an allocation is attempted after the task already OOMed, allow it to bypass the limit so that it can quickly finish the fault and invoke the OOM killer. Reported-by: NazurIt <azurit@pobox.sk> Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: <stable@kernel.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
- 09 10月, 2013 19 次提交
-
-
由 Rik van Riel 提交于
Shared faults can lead to lots of unnecessary page migrations, slowing down the system, and causing private faults to hit the per-pgdat migration ratelimit. This patch adds sysctl numa_balancing_migrate_deferred, which specifies how many shared page migrations to skip unconditionally, after each page migration that is skipped because it is a shared fault. This reduces the number of page migrations back and forth in shared fault situations. It also gives a strong preference to the tasks that are already running where most of the memory is, and to moving the other tasks to near the memory. Testing this with a much higher scan rate than the default still seems to result in fewer page migrations than before. Memory seems to be somewhat better consolidated than previously, with multi-instance specjbb runs on a 4 node system. Signed-off-by: NRik van Riel <riel@redhat.com> Signed-off-by: NMel Gorman <mgorman@suse.de> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-62-git-send-email-mgorman@suse.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
-
由 Rik van Riel 提交于
With the scan rate code working (at least for multi-instance specjbb), the large hammer that is "sched: Do not migrate memory immediately after switching node" can be replaced with something smarter. Revert temporarily migration disabling and all traces of numa_migrate_seq. Signed-off-by: NRik van Riel <riel@redhat.com> Signed-off-by: NMel Gorman <mgorman@suse.de> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-61-git-send-email-mgorman@suse.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
-
由 Rik van Riel 提交于
Adjust numa_scan_period in task_numa_placement, depending on how much useful work the numa code can do. The more local faults there are in a given scan window the longer the period (and hence the slower the scan rate) during the next window. If there are excessive shared faults then the scan period will decrease with the amount of scaling depending on whether the ratio of shared/private faults. If the preferred node changes then the scan rate is reset to recheck if the task is properly placed. Signed-off-by: NRik van Riel <riel@redhat.com> Signed-off-by: NMel Gorman <mgorman@suse.de> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-59-git-send-email-mgorman@suse.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
-
由 Rik van Riel 提交于
Due to the way the pid is truncated, and tasks are moved between CPUs by the scheduler, it is possible for the current task_numa_fault to group together tasks that do not actually share memory together. This patch adds a few easy sanity checks to task_numa_fault, joining tasks together if they share the same tsk->mm, or if the fault was on a page with an elevated mapcount, in a shared VMA. Signed-off-by: NRik van Riel <riel@redhat.com> Signed-off-by: NMel Gorman <mgorman@suse.de> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-57-git-send-email-mgorman@suse.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
-
由 Ingo Molnar 提交于
Signed-off-by: NIngo Molnar <mingo@kernel.org> Reviewed-by: NRik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Signed-off-by: NIngo Molnar <mingo@kernel.org> Link: http://lkml.kernel.org/r/1381141781-10992-53-git-send-email-mgorman@suse.de
-
由 Rik van Riel 提交于
It is possible for a task in a numa group to call exec, and have the new (unrelated) executable inherit the numa group association from its former self. This has the potential to break numa grouping, and is trivial to fix. Signed-off-by: NRik van Riel <riel@redhat.com> Signed-off-by: NMel Gorman <mgorman@suse.de> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-51-git-send-email-mgorman@suse.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
-
由 Mel Gorman 提交于
This patch uses the fraction of faults on a particular node for both task and group, to figure out the best node to place a task. If the task and group statistics disagree on what the preferred node should be then a full rescan will select the node with the best combined weight. Signed-off-by: NMel Gorman <mgorman@suse.de> Reviewed-by: NRik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-50-git-send-email-mgorman@suse.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
-
由 Rik van Riel 提交于
A newly spawned thread inside a process should stay on the same NUMA node as its parent. This prevents processes from being "torn" across multiple NUMA nodes every time they spawn a new thread. Signed-off-by: NRik van Riel <riel@redhat.com> Signed-off-by: NMel Gorman <mgorman@suse.de> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-49-git-send-email-mgorman@suse.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
-
由 Peter Zijlstra 提交于
And here's a little something to make sure not the whole world ends up in a single group. As while we don't migrate shared executable pages, we do scan/fault on them. And since everybody links to libc, everybody ends up in the same group. Suggested-by: NRik van Riel <riel@redhat.com> Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Signed-off-by: NMel Gorman <mgorman@suse.de> Reviewed-by: NRik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Link: http://lkml.kernel.org/r/1381141781-10992-47-git-send-email-mgorman@suse.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
-
由 Mel Gorman 提交于
It is desirable to model from userspace how the scheduler groups tasks over time. This patch adds an ID to the numa_group and reports it via /proc/PID/status. Signed-off-by: NMel Gorman <mgorman@suse.de> Reviewed-by: NRik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-45-git-send-email-mgorman@suse.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
-
由 Peter Zijlstra 提交于
While parallel applications tend to align their data on the cache boundary, they tend not to align on the page or THP boundary. Consequently tasks that partition their data can still "false-share" pages presenting a problem for optimal NUMA placement. This patch uses NUMA hinting faults to chain tasks together into numa_groups. As well as storing the NID a task was running on when accessing a page a truncated representation of the faulting PID is stored. If subsequent faults are from different PIDs it is reasonable to assume that those two tasks share a page and are candidates for being grouped together. Note that this patch makes no scheduling decisions based on the grouping information. Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Signed-off-by: NMel Gorman <mgorman@suse.de> Reviewed-by: NRik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Link: http://lkml.kernel.org/r/1381141781-10992-44-git-send-email-mgorman@suse.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
-
由 Peter Zijlstra 提交于
Use the new stop_two_cpus() to implement migrate_swap(), a function that flips two tasks between their respective cpus. I'm fairly sure there's a less crude way than employing the stop_two_cpus() method, but everything I tried either got horribly fragile and/or complex. So keep it simple for now. The notable detail is how we 'migrate' tasks that aren't runnable anymore. We'll make it appear like we migrated them before they went to sleep. The sole difference is the previous cpu in the wakeup path, so we override this. Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Reviewed-by: NRik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: NMel Gorman <mgorman@suse.de> Link: http://lkml.kernel.org/r/1381141781-10992-39-git-send-email-mgorman@suse.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
-
由 Mel Gorman 提交于
When a preferred node is selected for a tasks there is an attempt to migrate the task to a CPU there. This may fail in which case the task will only migrate if the active load balancer takes action. This may never happen if the conditions are not right. This patch will check at NUMA hinting fault time if another attempt should be made to migrate the task. It will only make an attempt once every five seconds. Signed-off-by: NMel Gorman <mgorman@suse.de> Reviewed-by: NRik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-34-git-send-email-mgorman@suse.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
-
由 Mel Gorman 提交于
Ideally it would be possible to distinguish between NUMA hinting faults that are private to a task and those that are shared. This patch prepares infrastructure for separately accounting shared and private faults by allocating the necessary buffers and passing in relevant information. For now, all faults are treated as private and detection will be introduced later. Signed-off-by: NMel Gorman <mgorman@suse.de> Reviewed-by: NRik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-26-git-send-email-mgorman@suse.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
-
由 Mel Gorman 提交于
This patch favours moving tasks towards NUMA node that recorded a higher number of NUMA faults during active load balancing. Ideally this is self-reinforcing as the longer the task runs on that node, the more faults it should incur causing task_numa_placement to keep the task running on that node. In reality a big weakness is that the nodes CPUs can be overloaded and it would be more efficient to queue tasks on an idle node and migrate to the new node. This would require additional smarts in the balancer so for now the balancer will simply prefer to place the task on the preferred node for a PTE scans which is controlled by the numa_balancing_settle_count sysctl. Once the settle_count number of scans has complete the schedule is free to place the task on an alternative node if the load is imbalanced. [srikar@linux.vnet.ibm.com: Fixed statistics] Signed-off-by: NMel Gorman <mgorman@suse.de> Reviewed-by: NRik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> [ Tunable and use higher faults instead of preferred. ] Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-23-git-send-email-mgorman@suse.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
-
由 Mel Gorman 提交于
NUMA hinting fault counts and placement decisions are both recorded in the same array which distorts the samples in an unpredictable fashion. The values linearly accumulate during the scan and then decay creating a sawtooth-like pattern in the per-node counts. It also means that placement decisions are time sensitive. At best it means that it is very difficult to state that the buffer holds a decaying average of past faulting behaviour. At worst, it can confuse the load balancer if it sees one node with an artifically high count due to very recent faulting activity and may create a bouncing effect. This patch adds a second array. numa_faults stores the historical data which is used for placement decisions. numa_faults_buffer holds the fault activity during the current scan window. When the scan completes, numa_faults decays and the values from numa_faults_buffer are copied across. Signed-off-by: NMel Gorman <mgorman@suse.de> Reviewed-by: NRik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-22-git-send-email-mgorman@suse.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
-
由 Mel Gorman 提交于
This patch selects a preferred node for a task to run on based on the NUMA hinting faults. This information is later used to migrate tasks towards the node during balancing. Signed-off-by: NMel Gorman <mgorman@suse.de> Reviewed-by: NRik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-21-git-send-email-mgorman@suse.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
-
由 Mel Gorman 提交于
This patch tracks what nodes numa hinting faults were incurred on. This information is later used to schedule a task on the node storing the pages most frequently faulted by the task. Signed-off-by: NMel Gorman <mgorman@suse.de> Reviewed-by: NRik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-20-git-send-email-mgorman@suse.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
-
由 Mel Gorman 提交于
The NUMA PTE scan rate is controlled with a combination of the numa_balancing_scan_period_min, numa_balancing_scan_period_max and numa_balancing_scan_size. This scan rate is independent of the size of the task and as an aside it is further complicated by the fact that numa_balancing_scan_size controls how many pages are marked pte_numa and not how much virtual memory is scanned. In combination, it is almost impossible to meaningfully tune the min and max scan periods and reasoning about performance is complex when the time to complete a full scan is is partially a function of the tasks memory size. This patch alters the semantic of the min and max tunables to be about tuning the length time it takes to complete a scan of a tasks occupied virtual address space. Conceptually this is a lot easier to understand. There is a "sanity" check to ensure the scan rate is never extremely fast based on the amount of virtual memory that should be scanned in a second. The default of 2.5G seems arbitrary but it is to have the maximum scan rate after the patch roughly match the maximum scan rate before the patch was applied. On a similar note, numa_scan_period is in milliseconds and not jiffies. Properly placed pages slow the scanning rate but adding 10 jiffies to numa_scan_period means that the rate scanning slows depends on HZ which is confusing. Get rid of the jiffies_to_msec conversion and treat it as ms. Signed-off-by: NMel Gorman <mgorman@suse.de> Reviewed-by: NRik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-18-git-send-email-mgorman@suse.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
-
- 28 9月, 2013 1 次提交
-
-
由 Peter Zijlstra 提交于
Yuanhan reported a serious throughput regression in his pigz benchmark. Using the ftrace patch I found that several idle paths need more TLC before we can switch the generic need_resched() over to preempt_need_resched. The preemption paths benefit most from preempt_need_resched and do indeed use it; all other need_resched() users don't really care that much so reverting need_resched() back to tif_need_resched() is the simple and safe solution. Reported-by: NYuanhan Liu <yuanhan.liu@linux.intel.com> Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Cc: Huang Ying <ying.huang@intel.com> Cc: lkp@linux.intel.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/20130927153003.GF15690@laptop.programming.kicks-ass.netSigned-off-by: NIngo Molnar <mingo@kernel.org>
-
- 25 9月, 2013 4 次提交
-
-
由 Peter Zijlstra 提交于
When using per-cpu preempt_count variables we need to save/restore the preempt_count on context switch (into per task storage; for instance the old thread_info::preempt_count variable) because of PREEMPT_ACTIVE. However, this means that on fork() the preempt_count value of the last context switch gets copied and if we had a PREEMPT_ACTIVE switch right before cloning a child task the child task will now too have PREEMPT_ACTIVE set and start its life with an extra PREEMPT_ACTIVE count. Therefore we need to make init_task_preempt_count() unconditional; this resets whatever preempt_count we inherited from our parent process. Doing so for !per-cpu implementations is harmless. For !PREEMPT_COUNT kernels we need to be careful not to start life with an increased preempt_count. Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/n/tip-4k0b7oy1rcdyzochwiixuwi9@git.kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
-
由 Peter Zijlstra 提交于
Rewrite the preempt_count macros in order to extract the 3 basic preempt_count value modifiers: __preempt_count_add() __preempt_count_sub() and the new: __preempt_count_dec_and_test() And since we're at it anyway, replace the unconventional $op_preempt_count names with the more conventional preempt_count_$op. Since these basic operators are equivalent to the previous _notrace() variants, do away with the _notrace() versions. Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/n/tip-ewbpdbupy9xpsjhg960zwbv8@git.kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
-
由 Peter Zijlstra 提交于
In order to combine the preemption and need_resched test we need to fold the need_resched information into the preempt_count value. Since the NEED_RESCHED flag is set across CPUs this needs to be an atomic operation, however we very much want to avoid making preempt_count atomic, therefore we keep the existing TIF_NEED_RESCHED infrastructure in place but at 3 sites test it and fold its value into preempt_count; namely: - resched_task() when setting TIF_NEED_RESCHED on the current task - scheduler_ipi() when resched_task() sets TIF_NEED_RESCHED on a remote task it follows it up with a reschedule IPI and we can modify the cpu local preempt_count from there. - cpu_idle_loop() for when resched_task() found tsk_is_polling(). We use an inverted bitmask to indicate need_resched so that a 0 means both need_resched and !atomic. Also remove the barrier() in preempt_enable() between preempt_enable_no_resched() and preempt_check_resched() to avoid having to reload the preemption value and allow the compiler to use the flags of the previuos decrement. I couldn't come up with any sane reason for this barrier() to be there as preempt_enable_no_resched() already has a barrier() before doing the decrement. Suggested-by: NIngo Molnar <mingo@kernel.org> Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/n/tip-7a7m5qqbn5pmwnd4wko9u6da@git.kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
-
由 Peter Zijlstra 提交于
Mike reported that commit 7d1a9417 ("x86: Use generic idle loop") regressed several workloads and caused excessive reschedule interrupts. The patch in question failed to notice that the x86 code had an inverted sense of the polling state versus the new generic code (x86: default polling, generic: default !polling). Fix the two prominent x86 mwait based idle drivers and introduce a few new generic polling helpers (fixing the wrong smp_mb__after_clear_bit usage). Also switch the idle routines to using tif_need_resched() which is an immediate TIF_NEED_RESCHED test as opposed to need_resched which will end up being slightly different. Reported-by: NMike Galbraith <bitbucket@online.de> Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Cc: lenb@kernel.org Cc: tglx@linutronix.de Link: http://lkml.kernel.org/n/tip-nc03imb0etuefmzybzj7sprf@git.kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
-