From mboxrd@z Thu Jan  1 00:00:00 1970
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: [PATCH 14/18] writeback: control dirty pause time
Date: Mon, 12 Sep 2011 12:28:05 +0200
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References: <20110904015305.367445271@intel.com>
	 <20110904020916.460538138@intel.com> <1315324285.14232.16.camel@twins>
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Cc: "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,  Andrew
 Morton <akpm@linux-foundation.org>, Jan Kara <jack@suse.cz>, Christoph
 Hellwig <hch@lst.de>, Dave Chinner <david@fromorbit.com>, Greg Thelen
 <gthelen@google.com>, Minchan Kim <minchan.kim@gmail.com>,  Vivek Goyal
 <vgoyal@redhat.com>, Andrea Righi <arighi@develer.com>, linux-mm
 <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>
To: Wu Fengguang <fengguang.wu@intel.com>
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On Wed, 2011-09-07 at 10:02 +0800, Wu Fengguang wrote:
> > also, do the two other line segments connect on the transition
> > point?
>=20
> I guess we can simply unify the other two formulas into one:
>=20
>         } else if (period <=3D max_pause / 4 &&
>                  pages_dirtied >=3D current->nr_dirtied_pause) {
>                 current->nr_dirtied_pause =3D clamp_val(
> =3D=3D>                                     dirty_ratelimit * (max_pause =
/ 2) / HZ,
>                                         pages_dirtied + pages_dirtied / 8=
,
>                                         pages_dirtied * 4);
>         } else if (pause >=3D max_pause) {
>                 current->nr_dirtied_pause =3D 1 | clamp_val(
> =3D=3D>                                     dirty_ratelimit * (max_pause =
/ 2) / HZ,
>                                         pages_dirtied / 4,
>                                         pages_dirtied - pages_dirtied / 8=
);
>         }=20


There's still the clamping, that combined with the various conditionals
make it very hard to tell if the functions are connected or jump around.

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