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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no 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 34EB6C433E0 for ; Fri, 15 Jan 2021 08:47:51 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A0B6A23329 for ; Fri, 15 Jan 2021 08:47:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A0B6A23329 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 1A1268D013F; Fri, 15 Jan 2021 03:47:50 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 150838D0023; Fri, 15 Jan 2021 03:47:50 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 03FBB8D013F; Fri, 15 Jan 2021 03:47:49 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0165.hostedemail.com [216.40.44.165]) by kanga.kvack.org (Postfix) with ESMTP id E262E8D0023 for ; Fri, 15 Jan 2021 03:47:49 -0500 (EST) Received: from smtpin07.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id A8413181AEF32 for ; Fri, 15 Jan 2021 08:47:49 +0000 (UTC) X-FDA: 77707381458.07.fruit23_58091d92752e Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin07.hostedemail.com (Postfix) with ESMTP id 902471803F9A7 for ; Fri, 15 Jan 2021 08:47:49 +0000 (UTC) X-HE-Tag: fruit23_58091d92752e X-Filterd-Recvd-Size: 3279 Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by imf44.hostedemail.com (Postfix) with ESMTP for ; Fri, 15 Jan 2021 08:47:47 +0000 (UTC) IronPort-SDR: 3x2oaCd3AuzGn495P65/S7IucgrWOEcW3XaV8ClV8ifTim5ylbpell80dntOCKvkHVWO3bjYoA t6aQvpYK7qZQ== X-IronPort-AV: E=McAfee;i="6000,8403,9864"; a="165606029" X-IronPort-AV: E=Sophos;i="5.79,349,1602572400"; d="scan'208";a="165606029" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Jan 2021 00:47:43 -0800 IronPort-SDR: on8+Bxc11wN/xt986f7vAgSqLFvRKTLK70zFKK8TkcK1dLMvz+SQfPzAnK97FPsY7Z2ZFHm+Gz 7AewwwY1uGYw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.79,349,1602572400"; d="scan'208";a="354226722" Received: from yhuang-dev.sh.intel.com (HELO yhuang-dev) ([10.239.159.145]) by fmsmga008.fm.intel.com with ESMTP; 15 Jan 2021 00:47:38 -0800 From: "Huang\, Ying" To: Linus Torvalds Cc: huang ying , Matthew Wilcox , Andrew Morton , Linux-MM , Linux Kernel Mailing List , Peter Xu , Hugh Dickins , Johannes Weiner , Mel Gorman , Rik van Riel , Andrea Arcangeli , Michal Hocko , Dave Hansen , Tim Chen Subject: Re: [PATCH] mm: Free unused swap cache page in write protection fault handler References: <20210113024241.179113-1-ying.huang@intel.com> <20210113031142.GM35215@casper.infradead.org> Date: Fri, 15 Jan 2021 16:47:37 +0800 In-Reply-To: (Linus Torvalds's message of "Wed, 13 Jan 2021 13:09:31 -0800") Message-ID: <87sg72vb6e.fsf@yhuang-dev.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii 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: Linus Torvalds writes: > On Tue, Jan 12, 2021 at 9:24 PM huang ying wrote: >> > >> > Couldn't we just move it to the tail of the LRU list so it's reclaimed >> > first? Or is locking going to be a problem here? >> >> Yes. That's a way to reduce the disturbance to the page reclaiming. >> For LRU lock contention, is it sufficient to use another pagevec? > > I wonder if this is really worth it. I'd like to see numbers. > > Because in probably 99%+ of all cases, that LRU dance is only going to > hurt and add extra locking overhead and dirty caches. > > So I'd like to see some numbers that it actually helps measurably in > whatever paging-heavy case... OK. I will start from a simpler version and only use a pagevec if there's measurable difference. Best Regards, Huang, Ying