From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753928AbdCBDdp (ORCPT ); Wed, 1 Mar 2017 22:33:45 -0500 Received: from out0-143.mail.aliyun.com ([140.205.0.143]:44522 "EHLO out0-143.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753584AbdCBDdk (ORCPT ); Wed, 1 Mar 2017 22:33:40 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R141e4;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e02c03303;MF=hillf.zj@alibaba-inc.com;NM=1;PH=DS;RN=8;SC=85;SR=0;TI=SMTPD_---.7jbqCbh_1488425567; Reply-To: "Hillf Danton" From: "Hillf Danton" To: "'Johannes Weiner'" , "'Andrew Morton'" Cc: "'Jia He'" , "'Michal Hocko'" , "'Mel Gorman'" , , , References: <20170228214007.5621-1-hannes@cmpxchg.org> <20170228214007.5621-7-hannes@cmpxchg.org> In-Reply-To: <20170228214007.5621-7-hannes@cmpxchg.org> Subject: Re: [PATCH 6/9] mm: don't avoid high-priority reclaim on memcg limit reclaim Date: Thu, 02 Mar 2017 11:32:47 +0800 Message-ID: <078101d29305$aa290420$fe7b0c60$@alibaba-inc.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Mailer: Microsoft Outlook 14.0 Thread-Index: AQGushofxnzLnyVlk/YQjboYC5yEOwJRUhccobYcGaA= Content-Language: zh-cn Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On March 01, 2017 5:40 AM Johannes Weiner wrote: > > 246e87a93934 ("memcg: fix get_scan_count() for small targets") sought > to avoid high reclaim priorities for memcg by forcing it to scan a > minimum amount of pages when lru_pages >> priority yielded nothing. > This was done at a time when reclaim decisions like dirty throttling > were tied to the priority level. > > Nowadays, the only meaningful thing still tied to priority dropping > below DEF_PRIORITY - 2 is gating whether laptop_mode=1 is generally > allowed to write. But that is from an era where direct reclaim was > still allowed to call ->writepage, and kswapd nowadays avoids writes > until it's scanned every clean page in the system. Potential changes > to how quick sc->may_writepage could trigger are of little concern. > > Remove the force_scan stuff, as well as the ugly multi-pass target > calculation that it necessitated. > > Signed-off-by: Johannes Weiner > --- Acked-by: Hillf Danton From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f70.google.com (mail-pg0-f70.google.com [74.125.83.70]) by kanga.kvack.org (Postfix) with ESMTP id 8289A6B0387 for ; Wed, 1 Mar 2017 22:32:55 -0500 (EST) Received: by mail-pg0-f70.google.com with SMTP id x17so78340703pgi.3 for ; Wed, 01 Mar 2017 19:32:55 -0800 (PST) Received: from out0-129.mail.aliyun.com (out0-129.mail.aliyun.com. [140.205.0.129]) by mx.google.com with ESMTP id r26si6271054pge.381.2017.03.01.19.32.54 for ; Wed, 01 Mar 2017 19:32:54 -0800 (PST) Reply-To: "Hillf Danton" From: "Hillf Danton" References: <20170228214007.5621-1-hannes@cmpxchg.org> <20170228214007.5621-7-hannes@cmpxchg.org> In-Reply-To: <20170228214007.5621-7-hannes@cmpxchg.org> Subject: Re: [PATCH 6/9] mm: don't avoid high-priority reclaim on memcg limit reclaim Date: Thu, 02 Mar 2017 11:32:47 +0800 Message-ID: <078101d29305$aa290420$fe7b0c60$@alibaba-inc.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Content-Language: zh-cn Sender: owner-linux-mm@kvack.org List-ID: To: 'Johannes Weiner' , 'Andrew Morton' Cc: 'Jia He' , 'Michal Hocko' , 'Mel Gorman' , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@fb.com On March 01, 2017 5:40 AM Johannes Weiner wrote: > > 246e87a93934 ("memcg: fix get_scan_count() for small targets") sought > to avoid high reclaim priorities for memcg by forcing it to scan a > minimum amount of pages when lru_pages >> priority yielded nothing. > This was done at a time when reclaim decisions like dirty throttling > were tied to the priority level. > > Nowadays, the only meaningful thing still tied to priority dropping > below DEF_PRIORITY - 2 is gating whether laptop_mode=1 is generally > allowed to write. But that is from an era where direct reclaim was > still allowed to call ->writepage, and kswapd nowadays avoids writes > until it's scanned every clean page in the system. Potential changes > to how quick sc->may_writepage could trigger are of little concern. > > Remove the force_scan stuff, as well as the ugly multi-pass target > calculation that it necessitated. > > Signed-off-by: Johannes Weiner > --- Acked-by: Hillf Danton -- 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