Re: [PATCH RFC] time: drop do_sys_times spinlock

Peter Zijlstra
2014-08-13T17:53:45Z

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On Wed, Aug 13, 2014 at 01:50:24PM -0400, Rik van Riel wrote:
> On 08/13/2014 01:40 PM, Peter Zijlstra wrote:
>
> > So the problem with the above is the lack of fwd progress; if
> > there's enough clone()/exit() happening in the thread group (and
> > the more CPUs the more possible), we'll keep repeating.
>
> We can fall back to taking the lock if we circle around,
> or if there is a writer active when we are in seqcount_read,
> similar to what the semaphore (ipc/sem.c) code is doing.
>
> read_seqbegin_or_lock would do the trick...

Yep that would work.

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