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From: Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH] Add block device speciffic splice write method
Date: Wed, 22 Oct 2008 23:41:57 -0700
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Cc: Dmitri Monakhov <dmonakhov@openvz.org>,
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To: Jens Axboe <jens.axboe@oracle.com>
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On Thu, 23 Oct 2008 08:29:23 +0200 Jens Axboe <jens.axboe@oracle.com> wrote:

> > But really it'd be better if the throttling happened down in
> > pipe_to_file(), on a per-page basis.  As it stands we can dirty an
> > arbitrary number of pagecache pages without throttling.  I think?
> 
> That's pretty exactly why it isn't done in the actor, to avoid doing it
> per-page. As it's going to be PIPE_BUFFERS (16) pages max, I think this
> is better.
> 
> Back in the splice early days, the balance_dirty_pages() actually showed
> up in profiles when it was done on a per-page basis. So I'm reluctant to
> change it :-)

That's why (the misnamed) balance_dirty_pages_ratelimited() exists?