lkml.org 
[lkml]   [2010]   [Oct]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 5/6] Export ns irqtimes through /proc/stat -v1
From
Date
On Tue, 2010-10-26 at 11:45 +0200, Peter Zijlstra wrote:
> On Mon, 2010-10-25 at 15:30 -0700, Venkatesh Pallipadi wrote:
> > +static void irqtime_account_process_tick(struct task_struct *p, int user_tick,
> > + struct rq *rq)
> > +{
> > + cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy);
> > + cputime64_t tmp = cputime_to_cputime64(cputime_one_jiffy);
> > + struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
> > +
> > + if (irqtime_account_hi_update()) {
> > + cpustat->irq = cputime64_add(cpustat->irq, tmp);
> > + } else if (irqtime_account_si_update()) {
> > + cpustat->softirq = cputime64_add(cpustat->softirq, tmp);
> > + } else
>
> I'm still not sure about this else stmt, the above two conditions can
> basically 'eat' user/system ticks. What we need to show is that there is
> no bias towards either kind so the ratio is not affected -- can we make
> such an argument?

I think I can made a counter-argument: if either or both of these checks
are true we had system time in the last tick, hence there is a larger
chance this tick is a system tick.

Therefore it will not provide the same user/system ratio.

Hmm?

> > if (user_tick) {
> > + account_user_time(p, cputime_one_jiffy, one_jiffy_scaled);
> > + } else if (p == rq->idle) {
> > + account_idle_time(cputime_one_jiffy);
> > + } else if (p->flags & PF_VCPU) { /* System time or guest time */
> > + account_guest_time(p, cputime_one_jiffy, one_jiffy_scaled);
> > + } else {
> > + __account_system_time(p, cputime_one_jiffy, one_jiffy_scaled,
> > + &cpustat->system);
> > + }
> > +}



\
 
 \ /
  Last update: 2010-10-26 17:01    [W:0.042 / U:2.240 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site