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author | Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com> | 2009-03-31 16:56:03 +0900 |
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committer | Ingo Molnar <mingo@elte.hu> | 2009-04-01 16:44:16 +0200 |
commit | c5f8d99585d7b5b7e857fabf8aefd0174903a98c (patch) | |
tree | 504127a7d4b6a0e3aee56d0822e5e8b23f8062d7 /kernel/posix-cpu-timers.c | |
parent | 13b8bd0a5713bdf05659019badd7c0407984ece1 (diff) | |
download | kernel_goldelico_gta04-c5f8d99585d7b5b7e857fabf8aefd0174903a98c.zip kernel_goldelico_gta04-c5f8d99585d7b5b7e857fabf8aefd0174903a98c.tar.gz kernel_goldelico_gta04-c5f8d99585d7b5b7e857fabf8aefd0174903a98c.tar.bz2 |
posixtimers, sched: Fix posix clock monotonicity
Impact: Regression fix (against clock_gettime() backwarding bug)
This patch re-introduces a couple of functions, task_sched_runtime
and thread_group_sched_runtime, which was once removed at the
time of 2.6.28-rc1.
These functions protect the sampling of thread/process clock with
rq lock. This rq lock is required not to update rq->clock during
the sampling.
i.e.
The clock_gettime() may return
((accounted runtime before update) + (delta after update))
that is less than what it should be.
v2 -> v3:
- Rename static helper function __task_delta_exec()
to do_task_delta_exec() since -tip tree already has
a __task_delta_exec() of different version.
v1 -> v2:
- Revises comments of function and patch description.
- Add note about accuracy of thread group's runtime.
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: stable@kernel.org [2.6.28.x][2.6.29.x]
LKML-Reference: <49D1CC93.4080401@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/posix-cpu-timers.c')
-rw-r--r-- | kernel/posix-cpu-timers.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c index fa07da9..4318c30 100644 --- a/kernel/posix-cpu-timers.c +++ b/kernel/posix-cpu-timers.c @@ -224,7 +224,7 @@ static int cpu_clock_sample(const clockid_t which_clock, struct task_struct *p, cpu->cpu = virt_ticks(p); break; case CPUCLOCK_SCHED: - cpu->sched = p->se.sum_exec_runtime + task_delta_exec(p); + cpu->sched = task_sched_runtime(p); break; } return 0; @@ -240,18 +240,19 @@ static int cpu_clock_sample_group(const clockid_t which_clock, { struct task_cputime cputime; - thread_group_cputime(p, &cputime); switch (CPUCLOCK_WHICH(which_clock)) { default: return -EINVAL; case CPUCLOCK_PROF: + thread_group_cputime(p, &cputime); cpu->cpu = cputime_add(cputime.utime, cputime.stime); break; case CPUCLOCK_VIRT: + thread_group_cputime(p, &cputime); cpu->cpu = cputime.utime; break; case CPUCLOCK_SCHED: - cpu->sched = cputime.sum_exec_runtime + task_delta_exec(p); + cpu->sched = thread_group_sched_runtime(p); break; } return 0; |