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author | Linus Torvalds <torvalds@linux-foundation.org> | 2014-04-01 19:16:10 +0200 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-04-01 19:16:10 +0200 |
commit | a21e40877ad130de837b0394583e4f68dc2ab6c5 (patch) | |
tree | c990fba6ef5f2ed464c906615c5c327f2d02b318 /kernel/sched | |
parent | Merge branch 'x86-cpufeature-for-linus' of git://git.kernel.org/pub/scm/linux... (diff) | |
parent | arch: Remove stub cputime.h headers (diff) | |
download | linux-a21e40877ad130de837b0394583e4f68dc2ab6c5.tar.xz linux-a21e40877ad130de837b0394583e4f68dc2ab6c5.zip |
Merge branch 'timers-nohz-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer updates from Ingo Molnar:
"The main purpose is to fix a full dynticks bug related to
virtualization, where steal time accounting appears to be zero in
/proc/stat even after a few seconds of competing guests running busy
loops in a same host CPU. It's not a regression though as it was
there since the beginning.
The other commits are preparatory work to fix the bug and various
cleanups"
* 'timers-nohz-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
arch: Remove stub cputime.h headers
sched: Remove needless round trip nsecs <-> tick conversion of steal time
cputime: Fix jiffies based cputime assumption on steal accounting
cputime: Bring cputime -> nsecs conversion
cputime: Default implementation of nsecs -> cputime conversion
cputime: Fix nsecs_to_cputime() return type cast
Diffstat (limited to 'kernel/sched')
-rw-r--r-- | kernel/sched/core.c | 6 | ||||
-rw-r--r-- | kernel/sched/cputime.c | 16 | ||||
-rw-r--r-- | kernel/sched/sched.h | 10 |
3 files changed, 11 insertions, 21 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index a47902c687ae..d11a1768357d 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -823,19 +823,13 @@ static void update_rq_clock_task(struct rq *rq, s64 delta) #endif #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING if (static_key_false((¶virt_steal_rq_enabled))) { - u64 st; - steal = paravirt_steal_clock(cpu_of(rq)); steal -= rq->prev_steal_time_rq; if (unlikely(steal > delta)) steal = delta; - st = steal_ticks(steal); - steal = st * TICK_NSEC; - rq->prev_steal_time_rq += steal; - delta -= steal; } #endif diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c index 58624a65f124..a95097cb4591 100644 --- a/kernel/sched/cputime.c +++ b/kernel/sched/cputime.c @@ -258,16 +258,22 @@ static __always_inline bool steal_account_process_tick(void) { #ifdef CONFIG_PARAVIRT if (static_key_false(¶virt_steal_enabled)) { - u64 steal, st = 0; + u64 steal; + cputime_t steal_ct; steal = paravirt_steal_clock(smp_processor_id()); steal -= this_rq()->prev_steal_time; - st = steal_ticks(steal); - this_rq()->prev_steal_time += st * TICK_NSEC; + /* + * cputime_t may be less precise than nsecs (eg: if it's + * based on jiffies). Lets cast the result to cputime + * granularity and account the rest on the next rounds. + */ + steal_ct = nsecs_to_cputime(steal); + this_rq()->prev_steal_time += cputime_to_nsecs(steal_ct); - account_steal_time(st); - return st; + account_steal_time(steal_ct); + return steal_ct; } #endif return false; diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index f2de7a175620..c9007f28d3a2 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1216,16 +1216,6 @@ extern void update_idle_cpu_load(struct rq *this_rq); extern void init_task_runnable_average(struct task_struct *p); -#ifdef CONFIG_PARAVIRT -static inline u64 steal_ticks(u64 steal) -{ - if (unlikely(steal > NSEC_PER_SEC)) - return div_u64(steal, TICK_NSEC); - - return __iter_div_u64_rem(steal, TICK_NSEC, &steal); -} -#endif - static inline void inc_nr_running(struct rq *rq) { rq->nr_running++; |