From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [PATCH 2/5] writeback: dirty position control Date: Fri, 12 Aug 2011 15:04:19 +0200 Message-ID: <1313154259.6576.42.camel@twins> References: <20110806084447.388624428@intel.com> <20110806094526.733282037@intel.com> <1312811193.10488.33.camel@twins> <20110808141128.GA22080@localhost> <1312814501.10488.41.camel@twins> <20110808230535.GC7176@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Cc: "linux-fsdevel@vger.kernel.org" , Andrew Morton , Jan Kara , Christoph Hellwig , Dave Chinner , Greg Thelen , Minchan Kim , Vivek Goyal , Andrea Righi , linux-mm , LKML To: Wu Fengguang Return-path: Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org On Tue, 2011-08-09 at 19:20 +0200, Peter Zijlstra wrote: >=20 > Now all of the above would seem to suggest: >=20 > dirty_ratelimit :=3D ref_bw >=20 > However for that you use: >=20 > if (pos_bw < dirty_ratelimit && ref_bw < dirty_ratelimit) > dirty_ratelimit =3D max(ref_bw, pos_bw); >=20 > if (pos_bw > dirty_ratelimit && ref_bw > dirty_ratelimit) > dirty_ratelimit =3D min(ref_bw, pos_bw); >=20 > You have: >=20 > pos_bw =3D dirty_ratelimit * pos_ratio >=20 > Which is ref_bw without the write_bw/dirty_bw factor, this confuses me.. > why are you ignoring the shift in output vs input rate there?=20 Could you elaborate on this primary feedback loop? Its the one part I don't feel I actually understand well. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org