Messages in this thread | | | Subject | Re: [PATCH 6/6] Account ksoftirqd time as cpustat softirq -v1 | From | Peter Zijlstra <> | Date | Tue, 26 Oct 2010 11:50:18 +0200 |
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On Tue, 2010-10-26 at 11:33 +0200, Peter Zijlstra wrote: > On Mon, 2010-10-25 at 15:30 -0700, Venkatesh Pallipadi wrote: > > softirq time in ksoftirqd context is not accounted in ns granularity > > per cpu softirq stats, as we want that to be a part of ksoftirqd > > exec_runtime. > > > > Accounting them as softirq on /proc/stat separately. > > > > Tested-by: Shaun Ruffell <sruffell@digium.com> > > > > Signed-off-by: Venkatesh Pallipadi <venki@google.com> > > --- > > kernel/sched.c | 8 ++++++++ > > 1 files changed, 8 insertions(+), 0 deletions(-) > > > > diff --git a/kernel/sched.c b/kernel/sched.c > > index 49f6f61..0955050 100644 > > --- a/kernel/sched.c > > +++ b/kernel/sched.c > > @@ -3617,6 +3617,14 @@ static void irqtime_account_process_tick(struct task_struct *p, int user_tick, > > cpustat->irq = cputime64_add(cpustat->irq, tmp); > > } else if (irqtime_account_si_update()) { > > cpustat->softirq = cputime64_add(cpustat->softirq, tmp); > > + } else if (this_cpu_ksoftirqd() == p) { > > + /* > > + * ksoftirqd time do not get accounted in cpu_softirq_time. > > + * So, we have to handle it separately here. > > + * Also, p->stime needs to be updated for ksoftirqd. > > + */ > > + __account_system_time(p, cputime_one_jiffy, one_jiffy_scaled, > > + &cpustat->softirq); > > } else if (user_tick) { > > account_user_time(p, cputime_one_jiffy, one_jiffy_scaled); > > } else if (p == rq->idle) { > > > I'm somewhat confused by this patch.. This is significantly different > from the thing proposed last time around, which was to use: > > cpustat->softirq + this_cpu_ksoftirqd()->se.sum_exec_runtime > > The above looses the fine grained aspect of the accounting and simply > charges a whole jiffy if the current process happens to be ksoftirqd.
Btw, both these solutions can cause si + us + ni + sy > 100%, are we ok with that?
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