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Merge branch 'timers-nohz-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

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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
This commit is contained in:
Linus Torvalds
2014-04-01 10:16:10 -07:00
parent b9b16a7922 073d8224d2
commit a21e40877a
28 changed files with 48 additions and 62 deletions
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6
kernel/sched/core.c
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@@ -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((&paravirt_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

16
kernel/sched/cputime.c
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@@ -258,16 +258,22 @@ static __always_inline bool steal_account_process_tick(void)
{
#ifdef CONFIG_PARAVIRT
if (static_key_false(&paravirt_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;

10
kernel/sched/sched.h
View File

@@ -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++;