From: Johannes Stezenbach <js@sig21.net>
To: Florian Mickler <florian@mickler.org>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-fsdevel@vger.kernel.org
Subject: Re: block cache replacement strategy?
Date: Mon, 13 Sep 2010 17:21:38 +0200 [thread overview]
Message-ID: <20100913152138.GA16334@sig21.net> (raw)
In-Reply-To: <20100910160247.GA637@sig21.net>
On Fri, Sep 10, 2010 at 06:02:48PM +0200, Johannes Stezenbach wrote:
>
> Linear read heuristic might be a good guess, but it would
> be nice to hear a comment from a vm/fs expert which
> confirms this works as intended.
Apparently I'm unworthy to get a response from someone knowledgable :-(
Anyway I found lmdd (from lmbench) can do random reads,
and indeed causes the data to enter the block (page?) cache,
replacing the previous data.
Johannes
zzz:~# echo 3 >/proc/sys/vm/drop_caches
zzz:~# ./lmdd if=~js/qemu/test.img bs=1M count=1000
1000.0000 MB in 17.7554 secs, 56.3210 MB/sec
zzz:~# ./lmdd if=~js/qemu/test.img bs=1M count=1000
1000.0000 MB in 0.9112 secs, 1097.4178 MB/sec
zzz:~# ./lmdd if=~js/qemu/test2.img bs=1M count=1000 rand=1G norepeat=
norepeat on 238035072
norepeat on 724579648
1000.0000 MB in 21.4419 secs, 46.6376 MB/sec
zzz:~# ./lmdd if=~js/qemu/test2.img bs=1M count=1000 rand=1G norepeat=
norepeat on 238035072
norepeat on 724579648
1000.0000 MB in 14.3859 secs, 69.5125 MB/sec
zzz:~# ./lmdd if=~js/qemu/test2.img bs=1M count=1000 rand=1G norepeat=
norepeat on 238035072
norepeat on 724579648
1000.0000 MB in 0.8764 secs, 1141.0810 MB/sec
next prev parent reply other threads:[~2010-09-13 15:21 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-07 13:34 block cache replacement strategy? Johannes Stezenbach
2010-09-09 12:00 ` Johannes Stezenbach
2010-09-10 10:02 ` Florian Mickler
2010-09-10 16:02 ` Johannes Stezenbach
2010-09-13 15:21 ` Johannes Stezenbach [this message]
2010-09-13 19:09 ` dave b
2010-09-13 19:26 ` Johannes Stezenbach
2010-09-30 23:27 ` Jan Kara
2010-10-01 13:05 ` Johannes Stezenbach
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