From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C26B0C2BB1D for ; Fri, 13 Mar 2020 19:46:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 94E94206B7 for ; Fri, 13 Mar 2020 19:46:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726946AbgCMTqx (ORCPT ); Fri, 13 Mar 2020 15:46:53 -0400 Received: from out30-130.freemail.mail.aliyun.com ([115.124.30.130]:58973 "EHLO out30-130.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726477AbgCMTqw (ORCPT ); Fri, 13 Mar 2020 15:46:52 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R141e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e07417;MF=yang.shi@linux.alibaba.com;NM=1;PH=DS;RN=5;SR=0;TI=SMTPD_---0TsV0fqL_1584128807; Received: from US-143344MP.local(mailfrom:yang.shi@linux.alibaba.com fp:SMTPD_---0TsV0fqL_1584128807) by smtp.aliyun-inc.com(127.0.0.1); Sat, 14 Mar 2020 03:46:49 +0800 Subject: Re: [PATCH 1/2] mm: swap: make page_evictable() inline To: Shakeel Butt Cc: Vlastimil Babka , Andrew Morton , Linux MM , LKML References: <1584124476-76534-1-git-send-email-yang.shi@linux.alibaba.com> From: Yang Shi Message-ID: <520b3295-9fb8-04a7-6215-9bfda4f1a268@linux.alibaba.com> Date: Fri, 13 Mar 2020 12:46:46 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/13/20 12:33 PM, Shakeel Butt wrote: > On Fri, Mar 13, 2020 at 11:34 AM Yang Shi wrote: >> When backporting commit 9c4e6b1a7027 ("mm, mlock, vmscan: no more >> skipping pagevecs") to our 4.9 kernel, our test bench noticed around 10% >> down with a couple of vm-scalability's test cases (lru-file-readonce, >> lru-file-readtwice and lru-file-mmap-read). I didn't see that much down >> on my VM (32c-64g-2nodes). It might be caused by the test configuration, >> which is 32c-256g with NUMA disabled and the tests were run in root memcg, >> so the tests actually stress only one inactive and active lru. It >> sounds not very usual in mordern production environment. >> >> That commit did two major changes: >> 1. Call page_evictable() >> 2. Use smp_mb to force the PG_lru set visible >> >> It looks they contribute the most overhead. The page_evictable() is a >> function which does function prologue and epilogue, and that was used by >> page reclaim path only. However, lru add is a very hot path, so it >> sounds better to make it inline. However, it calls page_mapping() which >> is not inlined either, but the disassemble shows it doesn't do push and >> pop operations and it sounds not very straightforward to inline it. >> >> Other than this, it sounds smp_mb() is not necessary for x86 since >> SetPageLRU is atomic which enforces memory barrier already, replace it >> with smp_mb__after_atomic() in the following patch. >> >> With the two fixes applied, the tests can get back around 5% on that >> test bench and get back normal on my VM. Since the test bench >> configuration is not that usual and I also saw around 6% up on the >> latest upstream, so it sounds good enough IMHO. >> >> The below is test data (lru-file-readtwice throughput) against the v5.6-rc4: >> mainline w/ inline fix >> 150MB 154MB >> > What is the test setup for the above experiment? I would like to get a repro. Just startup a VM with two nodes, then run case-lru-file-readtwice or case-lru-file-readonce in vm-scalability in root memcg or with memcg disabled.  Then get the average throughput (dd result) from the test. Our test bench uses the script from lkp, but I just ran it manually. Single node VM should be more obvious showed in my test. > >> With this patch the throughput gets 2.67% up. The data with using >> smp_mb__after_atomic() is showed in the following patch. >> >> Fixes: 9c4e6b1a7027 ("mm, mlock, vmscan: no more skipping pagevecs") >> Cc: Shakeel Butt >> Cc: Vlastimil Babka >> Signed-off-by: Yang Shi >> --- >> include/linux/swap.h | 24 +++++++++++++++++++++++- >> mm/vmscan.c | 23 ----------------------- >> 2 files changed, 23 insertions(+), 24 deletions(-) >> >> diff --git a/include/linux/swap.h b/include/linux/swap.h >> index 1e99f7a..297eb66 100644 >> --- a/include/linux/swap.h >> +++ b/include/linux/swap.h >> @@ -374,7 +374,29 @@ extern unsigned long mem_cgroup_shrink_node(struct mem_cgroup *mem, >> #define node_reclaim_mode 0 >> #endif >> >> -extern int page_evictable(struct page *page); >> +/* >> + * page_evictable - test whether a page is evictable >> + * @page: the page to test >> + * >> + * Test whether page is evictable--i.e., should be placed on active/inactive >> + * lists vs unevictable list. >> + * >> + * Reasons page might not be evictable: >> + * (1) page's mapping marked unevictable >> + * (2) page is part of an mlocked VMA >> + * >> + */ >> +static inline int page_evictable(struct page *page) >> +{ >> + int ret; >> + >> + /* Prevent address_space of inode and swap cache from being freed */ >> + rcu_read_lock(); >> + ret = !mapping_unevictable(page_mapping(page)) && !PageMlocked(page); >> + rcu_read_unlock(); >> + return ret; >> +} >> + >> extern void check_move_unevictable_pages(struct pagevec *pvec); >> >> extern int kswapd_run(int nid); >> diff --git a/mm/vmscan.c b/mm/vmscan.c >> index 8763705..855c395 100644 >> --- a/mm/vmscan.c >> +++ b/mm/vmscan.c >> @@ -4277,29 +4277,6 @@ int node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned int order) >> } >> #endif >> >> -/* >> - * page_evictable - test whether a page is evictable >> - * @page: the page to test >> - * >> - * Test whether page is evictable--i.e., should be placed on active/inactive >> - * lists vs unevictable list. >> - * >> - * Reasons page might not be evictable: >> - * (1) page's mapping marked unevictable >> - * (2) page is part of an mlocked VMA >> - * >> - */ >> -int page_evictable(struct page *page) >> -{ >> - int ret; >> - >> - /* Prevent address_space of inode and swap cache from being freed */ >> - rcu_read_lock(); >> - ret = !mapping_unevictable(page_mapping(page)) && !PageMlocked(page); >> - rcu_read_unlock(); >> - return ret; >> -} >> - >> /** >> * check_move_unevictable_pages - check pages for evictability and move to >> * appropriate zone lru list >> -- >> 1.8.3.1 >>