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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 350A9C4363D for ; Fri, 2 Oct 2020 08:40:48 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A2809206B8 for ; Fri, 2 Oct 2020 08:40:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A2809206B8 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id E12186B005D; Fri, 2 Oct 2020 04:40:46 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id DC1D06B0062; Fri, 2 Oct 2020 04:40:46 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CD81E6B0068; Fri, 2 Oct 2020 04:40:46 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0207.hostedemail.com [216.40.44.207]) by kanga.kvack.org (Postfix) with ESMTP id 9CE6B6B005D for ; Fri, 2 Oct 2020 04:40:46 -0400 (EDT) Received: from smtpin24.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 242A4180AD802 for ; Fri, 2 Oct 2020 08:40:46 +0000 (UTC) X-FDA: 77326339692.24.girl99_250016c271a2 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin24.hostedemail.com (Postfix) with ESMTP id ECA061A4A5 for ; Fri, 2 Oct 2020 08:40:45 +0000 (UTC) X-HE-Tag: girl99_250016c271a2 X-Filterd-Recvd-Size: 2073 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf32.hostedemail.com (Postfix) with ESMTP for ; Fri, 2 Oct 2020 08:40:45 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 3B40CAE79; Fri, 2 Oct 2020 08:40:44 +0000 (UTC) Date: Fri, 2 Oct 2020 09:40:42 +0100 From: Mel Gorman To: Michal Hocko Cc: Sebastiaan Meijer , akpm@linux-foundation.org, buddy.lumpkin@oracle.com, hannes@cmpxchg.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, riel@surriel.com, willy@infradead.org Subject: Re: [RFC PATCH 1/1] vmscan: Support multiple kswapd threads per node Message-ID: <20201002084042.GB3165@suse.de> References: <20201001123032.GC22560@dhcp22.suse.cz> <20201002070333.GA21871@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20201002070333.GA21871@dhcp22.suse.cz> User-Agent: Mutt/1.10.1 (2018-07-13) 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 Fri, Oct 02, 2020 at 09:03:33AM +0200, Michal Hocko wrote: > > > My recollection of the particular patch is dimm but I do remember it > > > tried to add more kswapd threads which would just paper over the problem > > > you are seein rather than solve it. > > > > Yeah, that's exactly what it does, just adding more kswap threads. > > Which is far from trivial because it has its side effects on the over > system balanc. While I have not read the original patches, multiple kswapd threads will smash into the LRU lock repeatedly. It's already the case that just plain storms of page cache allocations hammer that lock on pagevec releases and gets worse as memory sizes increase. Increasing LRU lock contention when memory is low is going to have diminishing returns. -- Mel Gorman SUSE Labs