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| author | Frederic Weisbecker <fweisbec@gmail.com> | 2012-12-16 20:00:34 +0100 |
|---|---|---|
| committer | Frederic Weisbecker <fweisbec@gmail.com> | 2013-01-27 20:35:47 +0100 |
| commit | 6a61671bb2f3a1bd12cd17b8fca811a624782632 (patch) | |
| tree | 0afc2915fb7e517472710a49a524510322dd5baa /kernel/fork.c | |
| parent | c11f11fcbdb5be790c565aed46411486a7586afc (diff) | |
| download | linux-6a61671bb2f3a1bd12cd17b8fca811a624782632.tar.gz linux-6a61671bb2f3a1bd12cd17b8fca811a624782632.tar.bz2 linux-6a61671bb2f3a1bd12cd17b8fca811a624782632.zip | |
cputime: Safely read cputime of full dynticks CPUs
While remotely reading the cputime of a task running in a
full dynticks CPU, the values stored in utime/stime fields
of struct task_struct may be stale. Its values may be those
of the last kernel <-> user transition time snapshot and
we need to add the tickless time spent since this snapshot.
To fix this, flush the cputime of the dynticks CPUs on
kernel <-> user transition and record the time / context
where we did this. Then on top of this snapshot and the current
time, perform the fixup on the reader side from task_times()
accessors.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
[fixed kvm module related build errors]
Signed-off-by: Sedat Dilek <sedat.dilek@gmail.com>
Diffstat (limited to 'kernel/fork.c')
| -rw-r--r-- | kernel/fork.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/kernel/fork.c b/kernel/fork.c index 65ca6d27f24e..e68a95b4cf26 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1233,6 +1233,12 @@ static struct task_struct *copy_process(unsigned long clone_flags, #ifndef CONFIG_VIRT_CPU_ACCOUNTING p->prev_cputime.utime = p->prev_cputime.stime = 0; #endif +#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN + seqlock_init(&p->vtime_seqlock); + p->vtime_snap = 0; + p->vtime_snap_whence = VTIME_SLEEPING; +#endif + #if defined(SPLIT_RSS_COUNTING) memset(&p->rss_stat, 0, sizeof(p->rss_stat)); #endif |