Re: [RFC][PATCH] iowait statistics

[Denis Vlasenko]

On 15 May 2002 14:13, Rik van Riel wrote:
> On Wed, 15 May 2002, Denis Vlasenko wrote:
> > I think two patches for same kernel piece at the same time is
> > too many. Go ahead and code this if you want.
>
> OK, here it is.   Changes against yesterday's patch:
>
> 1) make sure idle time can never go backwards by incrementing
>    the idle time in the timer interrupt too (surely we can
>    take this overhead if we're idle anyway ;))
>
> 2) get_request_wait also raises nr_iowait_tasks (thanks akpm)
>
> This patch is against the latest 2.5 kernel from bk and
> pretty much untested. If you have the time, please test
> it and let me know if it works.

--- 1.73/kernel/sched.c Mon Apr 29 09:16:24 2002
+++ edited/kernel/sched.c       Wed May 15 12:58:18 2002
@@ -679,6 +679,10 @@
        if (p == rq->idle) {
		[*]
                if (local_bh_count(cpu) || local_irq_count(cpu) > 1)
                        kstat.per_cpu_system[cpu] += system;
+               else if (atomic_read(&nr_iowait_tasks) > 0)
+                       kstat.per_cpu_iowait[cpu] += system;
+               else
+                       kstat.per_cpu_idle[cpu] += system;

[*] Maybe add if(system!=0) there?
--
vda