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=-9.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY autolearn=unavailable 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 381C2C433E3 for ; Tue, 18 Aug 2020 03:22:33 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 042F420716 for ; Tue, 18 Aug 2020 03:22:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 042F420716 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 7E0576B0002; Mon, 17 Aug 2020 23:22:32 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 741E26B0005; Mon, 17 Aug 2020 23:22:32 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5E17B6B0006; Mon, 17 Aug 2020 23:22:32 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0093.hostedemail.com [216.40.44.93]) by kanga.kvack.org (Postfix) with ESMTP id 442D76B0002 for ; Mon, 17 Aug 2020 23:22:32 -0400 (EDT) Received: from smtpin18.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id EE2688248076 for ; Tue, 18 Aug 2020 03:22:31 +0000 (UTC) X-FDA: 77162241702.18.mark35_25080732701c Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin18.hostedemail.com (Postfix) with ESMTP id C5370100ED0F9 for ; Tue, 18 Aug 2020 03:22:31 +0000 (UTC) X-HE-Tag: mark35_25080732701c X-Filterd-Recvd-Size: 3442 Received: from out4436.biz.mail.alibaba.com (out4436.biz.mail.alibaba.com [47.88.44.36]) by imf02.hostedemail.com (Postfix) with ESMTP for ; Tue, 18 Aug 2020 03:22:30 +0000 (UTC) X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R101e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04357;MF=richard.weiyang@linux.alibaba.com;NM=1;PH=DS;RN=6;SR=0;TI=SMTPD_---0U668H2X_1597720937; Received: from localhost(mailfrom:richard.weiyang@linux.alibaba.com fp:SMTPD_---0U668H2X_1597720937) by smtp.aliyun-inc.com(127.0.0.1); Tue, 18 Aug 2020 11:22:17 +0800 Date: Tue, 18 Aug 2020 11:22:17 +0800 From: Wei Yang To: Alexander Duyck Cc: David Hildenbrand , Wei Yang , akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/page_reporting: the "page" must not be the list head Message-ID: <20200818032217.GA31960@L-31X9LVDL-1304.local> Reply-To: Wei Yang References: <20200817084836.29216-1-richard.weiyang@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: C5370100ED0F9 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam01 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Aug 17, 2020 at 09:05:32AM -0700, Alexander Duyck wrote: > > >On 8/17/2020 2:35 AM, David Hildenbrand wrote: >> On 17.08.20 10:48, Wei Yang wrote: >> > If "page" is the list head, list_for_each_entry_safe() would stop >> > iteration. >> > >> > Signed-off-by: Wei Yang >> > --- >> > mm/page_reporting.c | 2 +- >> > 1 file changed, 1 insertion(+), 1 deletion(-) >> > >> > diff --git a/mm/page_reporting.c b/mm/page_reporting.c >> > index 3bbd471cfc81..aaaa3605123d 100644 >> > --- a/mm/page_reporting.c >> > +++ b/mm/page_reporting.c >> > @@ -178,7 +178,7 @@ page_reporting_cycle(struct page_reporting_dev_info *prdev, struct zone *zone, >> > * the new head of the free list before we release the >> > * zone lock. >> > */ >> > - if (&page->lru != list && !list_is_first(&page->lru, list)) >> > + if (!list_is_first(&page->lru, list)) >> > list_rotate_to_front(&page->lru, list); >> > /* release lock before waiting on report processing */ >> > >> >> Is this a fix or a cleanup? If it's a fix, can this be reproduced easily >> and what ere the effects? >> > >This should be a clean-up. Since the &page->lru != list will always be true. > >If I recall at some point the that was a check for &next->lru != list but I >think I pulled out an additional conditional check somewhere so that we just >go through the start of the loop again and iterate over reported pages until >we are guaranteed to have a non-reported page to rotate to the top of the >list with the general idea being that we wanted the allocator to pull >non-reported pages before reported pages. Hi, Alexander, I see you mentioned in the changelog, this change "mm/page_reporting: rotate reported pages to the tail of the list" brings some performance gain. Would you mind sharing more test detail? I would like to have a try at my side. Thanks :-) -- Wei Yang Help you, Help me