Re: [PATCH] RCU for low latency (experimental)

Takashi Iwai
2004-03-28T17:28:51Z

At Sun, 28 Mar 2004 22:50:36 +0530,
Dipankar Sarma wrote:
>
> On Sun, Mar 28, 2004 at 06:53:47PM +0200, Takashi Iwai wrote:
>
> > it seems count is never incremented in your patch...
> > or am i missing something?
>
> I messed it up when I forward ported the throttle-rcu.patch
> from 2.6.0+lots-of-instrumentation to 2.6.4-vanilla in order
> to publish in lkml. The original patch did this -

thans for the patch. i expected the similar fix :)

> > anyway, i confirmed that with the original krcud patch the latency
> > with dcache flood can be eliminated.
>
> Does the throttle-rcu patch also help eliminate dcache flood ? You
> can try by just changing count >= rcumaxbatch to ++count > rcumaxbatch.

i'll try it later.

> > for the non-preemptive case, rcu_bh_callback_limit() should return
> > bhlimit always, though. otherwise cond_resched() isn't called in the
> > callback loop properly.
>
> Yes, I think we should consider using limiting even in the non-preemptive
> case.

you mean preemptive case?

Takashi