Re: [RFC,PATCH] RCUify single-thread case of clock_gettime()

From: Ingo Molnar
Date: Mon Oct 31 2005 - 16:50:26 EST



* Hugh Dickins <hugh@xxxxxxxxxxx> wrote:

> On Mon, 31 Oct 2005, Ingo Molnar wrote:
> > * Hugh Dickins <hugh@xxxxxxxxxxx> wrote:
> > >
> > > Not my area at all, but this looks really dodgy to me, Paul:
> > > could you explain it further?
> >
> > the patch below (included in the -rt tree) is the prerequisite. That's
> > what Paul's "requires RCU on task_struct" comment refers to.
>
> Thanks, Ingo: Sorry, Paul: I missed that it was an -rt patch: Ignore
> me.

btw., since the RCU-task-struct thing is beneficial to upstream SMP
kernels (even without any preempt option enabled), it should be
considered for upstream too. The tasklist_lock is one of our last
remaining monolithic and globally-bouncing locks. The patch i attached
to the previous mail is against the upstream kernel and implements the
RCU-task-struct logic, without any PREEMPT_RT dependency. (the -rt tree
is a collection of various preemption related patches, not just
PREEMPT_RT)

Ingo
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