Re: Bug in kernel 2.6.31, Slow wb_kupdate writeout

From: Wu Fengguang
Date: Wed Jul 29 2009 - 21:58:04 EST


On Thu, Jul 30, 2009 at 09:12:26AM +0800, Martin Bligh wrote:
> > I agree on the unification of kupdate and sync paths. In fact I had a
> > patch for doing this. And I'd recommend to do it in two patches:
> > one to fix the congestion case, another to do the code unification.
> >
> > The sync path don't care whether requeue_io() or redirty_tail() is
> > used, because they disregard the time stamps totally - only order of
> > inodes matters (ie. starvation), which is same for requeue_io()/redirty_tail().
>
> But, as I understand it, both paths share the same lists, so we still have
> to be consistent?

Then let's first unify the code, then fix the congestion case? :)

> Also, you set flags like more_io higher up in sync_sb_inodes() based on
> whether there's anything in s_more_io queue, so it still seems to have
> some effect to me?

Yes, maybe in some rare cases.
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