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From: Nick Piggin <piggin@cyberone.com.au>
To: Rik van Riel <riel@redhat.com>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
	Con Kolivas <kernel@kolivas.org>,
	Marc-Christian Petersen <m.c.p@wolk-project.de>
Subject: Re: [PATCH][CFT] blk-fair-batches vs 2.4.20-rc6
Date: Tue, 03 Jun 2003 10:10:30 +1000	[thread overview]
Message-ID: <3EDBE776.2020806@cyberone.com.au> (raw)
In-Reply-To: <Pine.LNX.4.44.0306020919530.29823-100000@chimarrao.boston.redhat.com>



Rik van Riel wrote:

> On Mon, 2 Jun 2003, Nick Piggin wrote:
>
>> Previously:
>> * request queue fills up
>> * process 1 calls get_request, sleeps
>> * a couple of requests are freed
>> * process 2 calls get_request, proceeds
>> * a couple of requests are freed
>> * process 2 calls get_request, proceeds
>> ...
>
>
> In an early 2.4 kernel I've caught a few processes sleeping
> in get_request_wait for 5 minutes or so, while other processes
> were allocating new requests at exactly the speed they were
> processed.
>
> Of course, a patch to fix the problem was shot down due to
> lower dbench performance ... good thing Andrew Morton has
> more sense than that.

Mmm... unfortunately nearly everywhere >1 threads compete for
a resource, it comes down to throughput vs latency.

I think this patch is valid. It does not seem to be the sole
cause of the hangs though... err, and its against 21-rc6,
sorry :P


      reply	other threads:[~2003-06-02 23:57 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-06-02 12:53 [PATCH][CFT] blk-fair-batches vs 2.4.20-rc6 Nick Piggin
2003-06-02 13:21 ` Rik van Riel
2003-06-03  0:10   ` Nick Piggin [this message]

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