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2008-07-04sched: fix accounting in task delay accounting & migrationAnkita Garg
On Thu, Jun 19, 2008 at 12:27:14PM +0200, Peter Zijlstra wrote: > On Thu, 2008-06-05 at 10:50 +0530, Ankita Garg wrote: > > > Thanks Peter for the explanation... > > > > I agree with the above and that is the reason why I did not see weird > > values with cpu_time. But, run_delay still would suffer skews as the end > > points for delta could be taken on different cpus due to migration (more > > so on RT kernel due to the push-pull operations). With the below patch, > > I could not reproduce the issue I had seen earlier. After every dequeue, > > we take the delta and start wait measurements from zero when moved to a > > different rq. > > OK, so task delay delay accounting is broken because it doesn't take > migration into account. > > What you've done is make it symmetric wrt enqueue, and account it like > > cpu0 cpu1 > > enqueue > <wait-d1> > dequeue > enqueue > <wait-d2> > run > > Where you add both d1 and d2 to the run_delay,.. right? > Thanks for reviewing the patch. The above is exactly what I have done. > This seems like a good fix, however it looks like the patch will break > compilation in !CONFIG_SCHEDSTATS && !CONFIG_TASK_DELAY_ACCT, of it > failing to provide a stub for sched_info_dequeue() in that case. Fixed. Pl. find the new patch below. Signed-off-by: Ankita Garg <ankita@in.ibm.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Gregory Haskins <ghaskins@novell.com> Cc: rostedt@goodmis.org Cc: suresh.b.siddha@intel.com Cc: aneesh.kumar@linux.vnet.ibm.com Cc: dhaval@linux.vnet.ibm.com Cc: vatsa@linux.vnet.ibm.com Cc: David Bahi <DBahi@novell.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-19sched, delay accounting: fix incorrect delay time when constantly waiting on ↵Bharath Ravi
runqueue This patch corrects the incorrect value of per process run-queue wait time reported by delay statistics. The anomaly was due to the following reason. When a process leaves the CPU and immediately starts waiting for CPU on the runqueue (which means it remains in the TASK_RUNNABLE state), the time of re-entry into the run-queue is never recorded. Due to this, the waiting time on the runqueue from this point of re-entry upto the next time it hits the CPU is not accounted for. This is solved by recording the time of re-entry of a process leaving the CPU in the sched_info_depart() function IF the process will go back to waiting on the run-queue. This IF condition is verified by checking whether the process is still in the TASK_RUNNABLE state. The patch was tested on 2.6.26-rc6 using two simple CPU hog programs. The values noted prior to the fix did not account for the time spent on the runqueue waiting. After the fix, the correct values were reported back to user space. Signed-off-by: Bharath Ravi <bharathravi1@gmail.com> Signed-off-by: Madhava K R <madhavakr@gmail.com> Cc: dhaval@linux.vnet.ibm.com Cc: vatsa@in.ibm.com Cc: balbir@in.ibm.com Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-05-29show_schedstat(): fix memleakAdrian Bunk
The Coverity checker spotted a memleak introduced by commit 39106dcf85285e78f3b290022122c76f851379b8 (cpumask: use new cpus_scnprintf function). It seems the kfree() got lost between v2 and v3 of this patch... Signed-off-by: Adrian Bunk <bunk@kernel.org> Cc: Mike Travis <travis@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19cpumask: use new cpus_scnprintf functionMike Travis
* Cleaned up references to cpumask_scnprintf() and added new cpulist_scnprintf() interfaces where appropriate. * Fix some small bugs (or code efficiency improvments) for various uses of cpumask_scnprintf. * Clean up some checkpatch errors. Signed-off-by: Mike Travis <travis@sgi.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-11-28sched: clean up kernel/sched_stat.hIngo Molnar
clean up kernel/sched_stat.h. Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-11-09sched: fix delay accounting regressionBalbir Singh
Fix the delay accounting regression introduced by commit 75d4ef16a6aa84f708188bada182315f80aab6fa. rq no longer has sched_info data associated with it. task_struct sched_info structure is used by delay accounting to provide back statistics to user space. also remove direct use of sched_clock() (which is not a valid thing to do anymore) and use rq->clock instead. Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-18sched: reduce schedstat variable overhead a bitKen Chen
schedstat is useful in investigating CPU scheduler behavior. Ideally, I think it is beneficial to have it on all the time. However, the cost of turning it on in production system is quite high, largely due to number of events it collects and also due to its large memory footprint. Most of the fields probably don't need to be full 64-bit on 64-bit arch. Rolling over 4 billion events will most like take a long time and user space tool can be made to accommodate that. I'm proposing kernel to cut back most of variable width on 64-bit system. (note, the following patch doesn't affect 32-bit system). Signed-off-by: Ken Chen <kenchen@google.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15sched: clean up schedstats, cnt -> countIngo Molnar
rename all 'cnt' fields and variables to the less yucky 'count' name. yuckage noticed by Andrew Morton. no change in code, other than the /proc/sched_debug bkl_count string got a bit larger: text data bss dec hex filename 38236 3506 24 41766 a326 sched.o.before 38240 3506 24 41770 a32a sched.o.after Signed-off-by: Ingo Molnar <mingo@elte.hu> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15sched: fix delay accounting performance regressionIngo Molnar
fix delay accounting performance regression - those sched_clock() calls are not needed. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-08-02[PATCH] sched: add schedstat_set() APIIngo Molnar
add the schedstat_set() API, to allow the reduction of CONFIG_SCHEDSTAT related #ifdefs. No code changed. Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-09sched: update delay-accounting to use CFS's precise statsBalbir Singh
update delay-accounting to use CFS's precise stats. Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-09sched: move code into kernel/sched_stats.hIngo Molnar
create sched_stats.h and move sched.c schedstats code into it. This cleans up sched.c a bit. no code changes are caused by this patch. Signed-off-by: Ingo Molnar <mingo@elte.hu>