Messages in this thread Patch in this message | | | Date | Thu, 24 Aug 2006 14:18:25 +0200 | From | Martin Schwidefsky <> | Subject | [patch] dubious process system time. |
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From: Martin Schwidefsky <schwidefsky@de.ibm.com>
[patch] dubious process system time.
The system time that is accounted to a process includes the time spent in three different contexts: normal system time, hardirq time and softirq time. To account hardirq time and sortirq time to a process seems wrong, because the process could just happen to run when the interrupt arrives that was caused by an i/o for a completly different process. And the sum over stime and cstime of all processes won't match cputstat->system either. The following patch changes the accounting of system time so that hardirq and softirq time are not accounted to a process anymore.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> ---
kernel/sched.c | 7 +++---- 1 files changed, 3 insertions(+), 4 deletions(-)
diff -urpN linux-2.6/kernel/sched.c linux-2.6-patched/kernel/sched.c --- linux-2.6/kernel/sched.c 2006-08-01 10:09:55.000000000 +0200 +++ linux-2.6-patched/kernel/sched.c 2006-08-24 13:42:40.000000000 +0200 @@ -2939,17 +2939,16 @@ void account_system_time(struct task_str struct rq *rq = this_rq(); cputime64_t tmp; - p->stime = cputime_add(p->stime, cputime); - /* Add system time to cpustat. */ tmp = cputime_to_cputime64(cputime); if (hardirq_count() - hardirq_offset) cpustat->irq = cputime64_add(cpustat->irq, tmp); else if (softirq_count()) cpustat->softirq = cputime64_add(cpustat->softirq, tmp); - else if (p != rq->idle) + else if (p != rq->idle) { + p->stime = cputime_add(p->stime, cputime); cpustat->system = cputime64_add(cpustat->system, tmp); - else if (atomic_read(&rq->nr_iowait) > 0) + } else if (atomic_read(&rq->nr_iowait) > 0) cpustat->iowait = cputime64_add(cpustat->iowait, tmp); else cpustat->idle = cputime64_add(cpustat->idle, tmp); - 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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