From: Martin Schwidefsky <[email protected]>
[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 <[email protected]>
---
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);
-
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