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authorRik van Riel <riel@redhat.com>2016-07-13 16:50:01 +0200
committerIngo Molnar <mingo@kernel.org>2016-07-14 10:42:34 +0200
commit57430218317e5b280a80582a139b26029c25de6c (patch)
tree41ae977e5963cb147c67a4acf2eab6319cdfcbe7 /init
parentcefef3a76287c9b51e946d312aea1637bb3a57ff (diff)
downloadop-kernel-dev-57430218317e5b280a80582a139b26029c25de6c.zip
op-kernel-dev-57430218317e5b280a80582a139b26029c25de6c.tar.gz
sched/cputime: Count actually elapsed irq & softirq time
Currently, if there was any irq or softirq time during 'ticks' jiffies, the entire period will be accounted as irq or softirq time. This is inaccurate if only a subset of the time was actually spent handling irqs, and could conceivably mis-count all of the ticks during a period as irq time, when there was some irq and some softirq time. This can actually happen when irqtime_account_process_tick is called from account_idle_ticks, which can pass a larger number of ticks down all at once. Fix this by changing irqtime_account_hi_update(), irqtime_account_si_update(), and steal_account_process_ticks() to work with cputime_t time units, and return the amount of time spent in each mode. Rename steal_account_process_ticks() to steal_account_process_time(), to reflect that time is now accounted in cputime_t, instead of ticks. Additionally, have irqtime_account_process_tick() take into account how much time was spent in each of steal, irq, and softirq time. The latter could help improve the accuracy of cputime accounting when returning from idle on a NO_HZ_IDLE CPU. Properly accounting how much time was spent in hardirq and softirq time will also allow the NO_HZ_FULL code to re-use these same functions for hardirq and softirq accounting. Signed-off-by: Rik van Riel <riel@redhat.com> [ Make nsecs_to_cputime64() actually return cputime64_t. ] Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Radim Krcmar <rkrcmar@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wanpeng Li <wanpeng.li@hotmail.com> Link: http://lkml.kernel.org/r/1468421405-20056-2-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
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