Re: [PATCH 00/45] some writeback experiments

From: Wu Fengguang
Date: Wed Oct 07 2009 - 10:46:35 EST


On Wed, Oct 07, 2009 at 10:26:32PM +0800, Theodore Ts'o wrote:
> On Wed, Oct 07, 2009 at 03:38:18PM +0800, Wu Fengguang wrote:
> >
> > The estimated writeback bandwidth is about 1/2 the real throughput
> > for ext2/3/4 and btrfs; noticeable bigger than real throughput for NFS; and
> > cannot be estimated at all for XFS. Very interesting..
>
> Can you expand on what you mean here? Estimated write bandwidth of
> what? And what are you comparing it against?

Please refer to [PATCH 21/45] writeback: estimate bdi write bandwidth
and patch 22, I have some numbers there :)

> I'm having trouble understanding your note (which I'm guessing you
> write fairly late at night? :-)

Sorry - I wrote that when I got tired on debugging ;)

Thanks,
Fengguang

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