Re: [patch] get_request starvation fix

From: Marcelo Tosatti (marcelo@conectiva.com.br)
Date: Fri Feb 15 2002 - 12:23:16 EST


On Tue, 12 Feb 2002, Andrew Morton wrote:

> Second version of this patch, incorporating Suparna's
> suggested simplification (the low-water mark was
> unnecessary).
>
> This patch is working well here. Hopefully it'll pop up
> in an rmap kernel soon.
>
> Bill Irwin has been doing some fairly extensive tuning
> and testing of this. Hopefully he'll come out with some
> numbers soon.
>
> I include the original description...

It seems the real gain (in latency) is caused by the FIFO behaviour.

That is, removing this hunk (against __get_request_wait())

- if (q->rq[rw].count < batch_requests)
+ if (q->rq[rw].count == 0)
                        schedule();

Would not make _much_ difference latency-wise. I'm I right or missing
something ?

Anyway, I would like to have the patch cleaned up for 2.4.19-pre (remove
the instrumentation stuff _and_ make it clear on the documentation that
READA requests are not being used in practice).

Thanks a lot for that, Andrew.

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/



This archive was generated by hypermail 2b29 : Fri Feb 15 2002 - 21:01:08 EST