Messages in this thread Patch in this message | | | Date | Mon, 29 Oct 2007 21:04:25 +0100 | From | Ingo Molnar <> | Subject | Re: [stable] 2.6.23 regression: top displaying 9999% CPU usage |
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* Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
> We'll I initially thought of it and then I remembered that the > regression occurs only when the accounting itself is inaccurate. I am > tempted to ack the removal, but I would like to get input from others. > Meanwhile, I'll try and see if I can fix the problem
i've got a patch from Peter queued up. (see below) This should fix the main issue.
Ingo
--------------------> Subject: sched: keep utime/stime monotonic From: Peter Zijlstra <a.p.zijlstra@chello.nl>
keep utime/stime monotonic.
cpustats use utime/stime as a ratio against sum_exec_runtime, as a consequence it can happen - when the ratio changes faster than time accumulates - that either can be appear to go backwards.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu> --- fs/proc/array.c | 3 ++- include/linux/sched.h | 1 + kernel/fork.c | 1 + 3 files changed, 4 insertions(+), 1 deletion(-)
Index: linux/fs/proc/array.c =================================================================== --- linux.orig/fs/proc/array.c +++ linux/fs/proc/array.c @@ -358,7 +358,8 @@ static cputime_t task_utime(struct task_ } utime = (clock_t)temp; - return clock_t_to_cputime(utime); + p->prev_utime = max(p->prev_utime, clock_t_to_cputime(utime)); + return p->prev_utime; } static cputime_t task_stime(struct task_struct *p) Index: linux/include/linux/sched.h =================================================================== --- linux.orig/include/linux/sched.h +++ linux/include/linux/sched.h @@ -1009,6 +1009,7 @@ struct task_struct { unsigned int rt_priority; cputime_t utime, stime, utimescaled, stimescaled; cputime_t gtime; + cputime_t prev_utime; unsigned long nvcsw, nivcsw; /* context switch counts */ struct timespec start_time; /* monotonic time */ struct timespec real_start_time; /* boot based time */ Index: linux/kernel/fork.c =================================================================== --- linux.orig/kernel/fork.c +++ linux/kernel/fork.c @@ -1056,6 +1056,7 @@ static struct task_struct *copy_process( p->gtime = cputime_zero; p->utimescaled = cputime_zero; p->stimescaled = cputime_zero; + p->prev_utime = cputime_zero; #ifdef CONFIG_TASK_XACCT p->rchar = 0; /* I/O counter: bytes read */ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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