From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rik van Riel Subject: Re: [patch 0/8] mm: thrash detection-based file cache sizing v5 Date: Thu, 14 Nov 2013 10:56:32 -0500 Message-ID: <5284F2B0.1080708@redhat.com> References: <1381441622-26215-1-git-send-email-hannes@cmpxchg.org> <5264F353.1080603@suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Johannes Weiner , Andrew Morton , Andi Kleen , Andrea Arcangeli , Greg Thelen , Christoph Hellwig , Hugh Dickins , Jan Kara , KOSAKI Motohiro , Mel Gorman , Minchan Kim , Peter Zijlstra , Michel Lespinasse , Seth Jennings , Roman Gushchin , Ozgun Erdogan , Metin Doslu , Tejun Heo , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org To: Vlastimil Babka Return-path: In-Reply-To: <5264F353.1080603@suse.cz> Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org On 10/21/2013 05:26 AM, Vlastimil Babka wrote: > On 10/10/2013 11:46 PM, Johannes Weiner wrote: >> Hi everyone, >> >> here is an update to the cache sizing patches for 3.13. >> >> Changes in this revision >> >> o Drop frequency synchronization between refaulted and demoted pages >> and just straight up activate refaulting pages whose access >> frequency indicates they could stay in memory. This was suggested >> by Rik van Riel a looong time ago but misinterpretation of test >> results during early stages of development took me a while to >> overcome. It's still the same overall concept, but a little simpler >> and with even faster cache adaptation. Yay! > > Oh, I liked the previous approach with direct competition between the > refaulted and demoted page :) Doesn't the new approach favor the > refaulted page too much? No wonder it leads to faster cache adaptation, > but could it also cause degradations for workloads that don't benefit > from it? Were there any tests for performance regressions on workloads > that were not the target of the patchset? This is a good question, and one that is probably best settled through experimentation. Even with the first scheme (fault refaulted page to the inactive list), those pages only need 2 accesses to be promoted to the active list. That is because a refault tends to immediately be followed by an access (after all, the attempted access causes the page to get loaded back into memory). -- 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/ . Don't email: email@kvack.org