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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