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| author | Frederic Weisbecker <fweisbec@gmail.com> | 2013-02-23 20:28:45 +0400 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2013-02-24 15:57:16 +0400 |
| commit | 7f6575f1fb963d5231afbceecd3feadb6ab58cd3 (patch) | |
| tree | b66acd09037319c1489e97e78f44b5dcdafda523 /kernel/sched/cputime.c | |
| parent | c78a4bcd1a879b39fb7646c887b0c195f1018909 (diff) | |
| download | linux-7f6575f1fb963d5231afbceecd3feadb6ab58cd3.tar.xz | |
cputime: Use local_clock() for full dynticks cputime accounting
Running the full dynticks cputime accounting with preemptible
kernel debugging trigger the following warning:
[ 4.488303] BUG: using smp_processor_id() in preemptible [00000000] code: init/1
[ 4.490971] caller is native_sched_clock+0x22/0x80
[ 4.493663] Pid: 1, comm: init Not tainted 3.8.0+ #13
[ 4.496376] Call Trace:
[ 4.498996] [<ffffffff813410eb>] debug_smp_processor_id+0xdb/0xf0
[ 4.501716] [<ffffffff8101e642>] native_sched_clock+0x22/0x80
[ 4.504434] [<ffffffff8101db99>] sched_clock+0x9/0x10
[ 4.507185] [<ffffffff81096ccd>] fetch_task_cputime+0xad/0x120
[ 4.509916] [<ffffffff81096dd5>] task_cputime+0x35/0x60
[ 4.512622] [<ffffffff810f146e>] acct_update_integrals+0x1e/0x40
[ 4.515372] [<ffffffff8117d2cf>] do_execve_common+0x4ff/0x5c0
[ 4.518117] [<ffffffff8117cf14>] ? do_execve_common+0x144/0x5c0
[ 4.520844] [<ffffffff81867a10>] ? rest_init+0x160/0x160
[ 4.523554] [<ffffffff8117d457>] do_execve+0x37/0x40
[ 4.526276] [<ffffffff810021a3>] run_init_process+0x23/0x30
[ 4.528953] [<ffffffff81867aac>] kernel_init+0x9c/0xf0
[ 4.531608] [<ffffffff8188356c>] ret_from_fork+0x7c/0xb0
We use sched_clock() to perform and fixup the cputime
accounting. However we are calling it with preemption enabled
from the read side, which trigger the bug above.
To fix this up, use local_clock() instead. It takes care of
preemption and also provide a more reliable clock source. This
is welcome for this kind of statistic that is widely relied on
in userspace.
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Reported-by: Ingo Molnar <mingo@kernel.org>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Kevin Hilman <khilman@linaro.org>
Link: http://lkml.kernel.org/r/1361636925-22288-3-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched/cputime.c')
| -rw-r--r-- | kernel/sched/cputime.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c index 9857329ed280..ed12cbb135f4 100644 --- a/kernel/sched/cputime.c +++ b/kernel/sched/cputime.c @@ -604,7 +604,7 @@ static unsigned long long vtime_delta(struct task_struct *tsk) { unsigned long long clock; - clock = sched_clock(); + clock = local_clock(); if (clock < tsk->vtime_snap) return 0; |