From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: [PATCH -mm] mm: fine-grained dirty_ratio_pcm and dirty_background_ratio_pcm (v2) Date: Mon, 10 Nov 2008 13:12:55 -0800 Message-ID: <20081110131255.ce71ce60.akpm@linux-foundation.org> References: <1221232192-13553-1-git-send-email-righi.andrea@gmail.com> <20080912131816.e0cfac7a.akpm@linux-foundation.org> <532480950809221641y3471267esff82a14be8056586@mail.gmail.com> <48EB4236.1060100@linux.vnet.ibm.com> <48EB851D.2030300@gmail.com> <20081008101642.fcfb9186.kamezawa.hiroyu@jp.fujitsu.com> <48ECB215.4040409@linux.vnet.ibm.com> <48EE236A.90007@gmail.com> <4918A074.1050003@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4918A074.1050003-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: righi.andrea-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org Cc: mrubin-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, dradford-cT2on/YLNlBWk0Htik3J/w@public.gmane.org, m.innocenti-qooieK91W7JeoWH0uzbU5w@public.gmane.org, fernando-gVGce1chcLdL9jVzuh4AOg@public.gmane.org, agk-9JcytcrH/bA+uJoB2kUjGw@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, chlunde-om2ZC0WAoZIXWF+eFR7m5Q@public.gmane.org, dave-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, dpshah-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, rientjes-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, matt-cT2on/YLNlBWk0Htik3J/w@public.gmane.org, menage-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, containers-qjLDD68F18O7TbgM5vRIOg@public.gmane.org, eric.rannaud-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, balbir-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org List-Id: containers.vger.kernel.org On Mon, 10 Nov 2008 21:58:28 +0100 Andrea Righi wrote: > The current granularity of 5% of dirtyable memory for dirty pages writeback is > too coarse for large memory machines and this will get worse as > memory-size/disk-speed ratio continues to increase. > > These large writebacks can be unpleasant for desktop or latency-sensitive > environments, where the time to complete each writeback can be perceived as a > lack of responsiveness by the whole system. > > Following there's a similar solution as discussed in [1], but a little > bit simplified in order to provide the same functionality (in particular > to avoid backward compatibility problems) and reduce the amount of code > needed to implement an in-kernel parser to handle percentages with > decimals digits. > > The kernel provides the following parameters: > - dirty_ratio, dirty_background_ratio in percentage (1 ... 100) > - dirty_ratio_pcm, dirty_background_ratio_pcm in units of percent mille (1 ... 100,000) hm, so how long until dirty_ratio_pcm becomes too coarse... What happened to the idea of specifying these in units of kilobytes?