Re: [PATCH 8/8] vm: Add an tuning knob for vm.max_writeback_mb

From: Wu Fengguang
Date: Wed Sep 09 2009 - 08:58:19 EST


On Wed, Sep 09, 2009 at 08:37:46PM +0800, Jens Axboe wrote:
> On Wed, Sep 09 2009, Wu Fengguang wrote:
> > On Wed, Sep 09, 2009 at 08:28:06PM +0800, Christoph Hellwig wrote:
> > > On Wed, Sep 09, 2009 at 05:29:01PM +0800, Wu Fengguang wrote:
> > > > It seems that balance_dirty_pages() is not coupled with MAX_WRITEBACK_PAGES.
> > > > Instead it uses the much smaller (ratelimit_pages + ratelimit_pages / 2).
> > >
> > > With Jen's writeback patches applied balance_dirty_pages does not start
> > > writeback itself anymore but calls bdi_start_writeback to let the
> > > flusher thread do it.
> > >
> > > it would be good if we do any writeback tuning ontop of these patches..
> >
> > Ah OK. I'm using latest linux-next and expected his patches to be there..
>
> They are there, have been for months! But I think Christoph is a little
> confused, we'll still do writeback inline from balance_dirty_pages(). It
> does writeback_inodes_wbc(), which does not schedule async writeout.
>
> So if your patches are based and tested off -next, you should be good.

Just found that I was in the wrong branch.. Now I see
writeback_inodes_wbc(), thanks.

Thanks,
Fengguang

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