From: Nick Piggin <piggin@cyberone.com.au>
To: Con Kolivas <kernel@kolivas.org>
Cc: linux kernel mailing list <linux-kernel@vger.kernel.org>
Subject: Re: Deadline for video capture
Date: Thu, 22 Jan 2004 16:17:25 +1100 [thread overview]
Message-ID: <400F5CE5.6000602@cyberone.com.au> (raw)
In-Reply-To: <200401221608.05924.kernel@kolivas.org>
Con Kolivas wrote:
>-----BEGIN PGP SIGNED MESSAGE-----
>Hash: SHA1
>
>Hi all
>
>I suspected that the anticipatory scheduler might not have been the best
>choice for video capture because of the interruption to writes by reads and
>the subsequent anticipatory delay associated with it. I have now confirmed
>that booting with the default anticipatory i/o elevator I get many dropped
>frames that I don't get if I boot with elevator=deadline.
>
>briefly: dual 7200 rpm ATA5 IDE drives in software RAID0
>
>I guess there isn't really a lot to do about this, it's a compromise one way
>or the other. The anticipatory scheduler seems better all round but in this
>large streaming write situation it doesn't seem ideal. Any sysctl settings I
>could use to blunt the anticipation just before I do video capture?
>
echo 0 > /sys/block/*/queue/iosched/antic_expire
Turns it off alltogether.
You could also adjust read and write batch expire settings which are
heavily biased toward reads.
next prev parent reply other threads:[~2004-01-22 5:18 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-01-22 5:08 Deadline for video capture Con Kolivas
2004-01-22 5:17 ` Nick Piggin [this message]
2004-01-22 14:28 ` Timothy Miller
2004-01-22 15:37 ` Con Kolivas
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