From: Wu Fengguang <fengguang.wu@intel.com>
To: Michael Rubin <mrubin@google.com>
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-mm@kvack.org, jack@suse.cz, riel@redhat.com,
akpm@linux-foundation.org, david@fromorbit.com, npiggin@suse.de,
hch@lst.de, axboe@kernel.dk
Subject: Re: [PATCH 2/3] writeback: Adding pages_dirtied and pages_entered_writeback
Date: Fri, 20 Aug 2010 14:54:29 +0800 [thread overview]
Message-ID: <20100820065429.GA6828@localhost> (raw)
In-Reply-To: <20100820025111.GB5502@localhost>
Sorry, here is the mentioned vmmon source file.
The full ext3-tools package is here:
http://userweb.kernel.org/~akpm/stuff/ext3-tools.tar.gz
Thanks,
Fengguang
On Fri, Aug 20, 2010 at 10:51:11AM +0800, Wu Fengguang wrote:
> On Thu, Aug 19, 2010 at 01:57:26PM -0700, Michael Rubin wrote:
> > To help developers and applications gain visibility into writeback
> > behaviour adding four read only sysctl files into /proc/sys/vm.
> > These files allow user apps to understand writeback behaviour over time
> > and learn how it is impacting their performance.
> >
> > # cat /proc/sys/vm/pages_dirtied
> > 3747
> > # cat /proc/sys/vm/pages_entered_writeback
> > 3618
>
> As Rik said, /proc/sys is not a suitable place.
>
> Frankly speaking I've worked on writeback for years and never felt
> the need to add these counters. What I often do is:
>
> $ vmmon -d 1 nr_writeback nr_dirty nr_unstable
>
> nr_writeback nr_dirty nr_unstable
> 68738 0 39568
> 66051 0 42255
> 63406 0 44900
> 60643 0 47663
> 57954 0 50352
> 55264 0 53042
> 52592 0 55715
> 49922 0 58385
> That is what I get when copying /dev/zero to NFS.
>
> You can find vmmon.c in Andrew Morton's ext3-tools package.
> Also attached for your convenience.
>
> I'm very interested in Google's use case for this patch, and why
> the simple /proc/vmstat based vmmon tool is not enough.
>
> Thanks,
> Fengguang
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next prev parent reply other threads:[~2010-08-20 6:54 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-19 20:57 [PATCH 0/3] writeback: kernel visibility Michael Rubin
2010-08-19 20:57 ` [PATCH 1/3] mm: helper functions for dirty and writeback accounting Michael Rubin
2010-08-20 2:34 ` Wu Fengguang
2010-08-20 8:19 ` Michael Rubin
2010-08-19 20:57 ` [PATCH 2/3] writeback: Adding pages_dirtied and pages_entered_writeback Michael Rubin
2010-08-20 2:51 ` Wu Fengguang
2010-08-20 6:54 ` Wu Fengguang [this message]
2010-08-20 8:16 ` Michael Rubin
2010-08-20 8:43 ` Wu Fengguang
2010-08-19 20:57 ` [PATCH 3/3] writeback: Reporting dirty thresholds in /proc/vmstat Michael Rubin
2010-08-20 3:16 ` Wu Fengguang
2010-08-20 8:18 ` Michael Rubin
2010-08-19 22:11 ` [PATCH 0/3] writeback: kernel visibility Rik van Riel
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