From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752154AbeC0BNd (ORCPT ); Mon, 26 Mar 2018 21:13:33 -0400 Received: from mail-pg0-f68.google.com ([74.125.83.68]:36541 "EHLO mail-pg0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751866AbeC0BNc (ORCPT ); Mon, 26 Mar 2018 21:13:32 -0400 X-Google-Smtp-Source: AG47ELvw/Egz5/vGhvG2Bdla/uXvHS8Snzvd+x7a4LwIkSMTTi9AQGVSZrjVlLCKf3dLGQXuaapiPw== Date: Tue, 27 Mar 2018 10:13:27 +0900 From: Sergey Senozhatsky To: Minchan Kim Cc: Sergey Senozhatsky , Andrew Morton , LKML Subject: Re: [PATCH 2/2] zram: idle memory tracking Message-ID: <20180327011327.GE467@jagdpanzerIV> References: <20180326064951.123940-1-minchan@kernel.org> <20180326064951.123940-2-minchan@kernel.org> <20180327004911.GA467@jagdpanzerIV> <20180327010347.GA41148@rodete-desktop-imager.corp.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180327010347.GA41148@rodete-desktop-imager.corp.google.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (03/27/18 10:03), Minchan Kim wrote: > On Tue, Mar 27, 2018 at 09:49:11AM +0900, Sergey Senozhatsky wrote: > > On (03/26/18 15:49), Minchan Kim wrote: > > > zRam as swap is useful for small memory device. However, swap means > > > those pages on zram are mostly cold pages due to VM's LRU algorithm. > > > Especially, once init data for application are touched for launching, > > > they tend to be not accessed any more and finally swapped out. > > > zRAM can store such cold pages as compressed form but it's pointless > > > to keep in memory. Better idea is app developers free them directly > > > rather than remaining them on heap. > > > > > > This patch tell us last accesss time of each block of zram via > > > "cat /sys/kernel/debug/zram/zram0/access_time". > > > > > > The output is as follows, > > > > > > 276 1250 > > > 277 1800 > > > .. .. > > > .. .. > > > > So can we just use CONFIG_IDLE_PAGE_TRACKING + CONFIG_PAGE_OWNER? > > The goal is not mapped memory tracking but one swapped out. > Can we do it by above two combination? Ah, you are right. page_idle tracks only pages which are on LRU lists. > Furthermore, I am planning to provide incompressible pages as well > as access time so I will change interface at v2. OK. -ss