Re: [PATCH 2/2] CFS CGroup: Report usage

From: Srivatsa Vaddagiri
Date: Tue Oct 23 2007 - 12:29:24 EST


On Mon, Oct 22, 2007 at 11:06:54PM -0700, Paul Menage wrote:
> > > + for_each_possible_cpu(i) {
> > > + unsigned long flags;
> > > + spin_lock_irqsave(&tg->cfs_rq[i]->rq->lock, flags);
> >
> > Is the lock absolutely required here?
>
> I'm not sure, I was hoping you or Ingo could comment on this. But some
> kind of locking seems to required at least on 32-bit platforms, since
> sum_exec_runtime is a 64-bit number.

I tend to agree abt 32-bit platforms requiring a lock to read the 64-bit
sum_exec_runtime field.

Ingo/Dmitry, what do you think? fs/proc/array.c:task_utime() is also
buggy in that case.

--
Regards,
vatsa
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