From: Florian Mickler <florian@mickler.org>
To: linux-mm@kvack.org
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: block cache replacement strategy?
Date: Fri, 10 Sep 2010 12:02:35 +0200 [thread overview]
Message-ID: <20100910120235.455962c4@schatten.dmk.lab> (raw)
In-Reply-To: <20100909120044.GA27765@sig21.net>
On Thu, 9 Sep 2010 14:00:44 +0200
Johannes Stezenbach <js@sig21.net> wrote:
> On Tue, Sep 07, 2010 at 03:34:29PM +0200, Johannes Stezenbach wrote:
> >
> > during some simple disk read throughput testing I observed
> > caching behaviour that doesn't seem right. The machine
> > has 2G of RAM and AMD Athlon 4850e, x86_64 kernel but 32bit
> > userspace, Linux 2.6.35.4. It seems that contents of the
> > block cache are not evicted to make room for other blocks.
> > (Or something like that, I have no real clue about this.)
> >
> > Since this is a rather artificial test I'm not too worried,
> > but it looks strange to me so I thought I better report it.
>
> C'mon guys, please comment. Is this a bug or not?
> Or is my question too silly?
>
>
> Johannes
Well I personally have no clue about the block caching, but perhaps
that is an heuristic to prevent the cache from fluctuating too much?
Some minimum time a block is hold... in a big linear read the cache is
useless anyway most of the time, so it could make some sense...
You could try accessing random files after filling up the cache and
check if those evict the the cache. That should rule out any
linear-read-detection heuristic.
Cheers,
Flo
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2010-09-10 10:30 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-07 13:34 Johannes Stezenbach
2010-09-09 12:00 ` Johannes Stezenbach
2010-09-10 10:02 ` Florian Mickler [this message]
2010-09-10 16:02 ` Johannes Stezenbach
2010-09-13 15:21 ` Johannes Stezenbach
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20100910120235.455962c4@schatten.dmk.lab \
--to=florian@mickler.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox