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=-5.3 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 362A3C47093 for ; Tue, 1 Jun 2021 12:45:39 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id AF3AE6135D for ; Tue, 1 Jun 2021 12:45:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AF3AE6135D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=techsingularity.net Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 0E0796B009E; Tue, 1 Jun 2021 08:45:38 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 069806B00B0; Tue, 1 Jun 2021 08:45:37 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E24E96B00B9; Tue, 1 Jun 2021 08:45:37 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0116.hostedemail.com [216.40.44.116]) by kanga.kvack.org (Postfix) with ESMTP id ACAAF6B009E for ; Tue, 1 Jun 2021 08:45:37 -0400 (EDT) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 3C9BD181AEF10 for ; Tue, 1 Jun 2021 12:45:37 +0000 (UTC) X-FDA: 78205126314.14.4D08EFB Received: from outbound-smtp24.blacknight.com (outbound-smtp24.blacknight.com [81.17.249.192]) by imf16.hostedemail.com (Postfix) with ESMTP id D09048019377 for ; Tue, 1 Jun 2021 12:45:24 +0000 (UTC) Received: from mail.blacknight.com (pemlinmail01.blacknight.ie [81.17.254.10]) by outbound-smtp24.blacknight.com (Postfix) with ESMTPS id D0CD2C0C55 for ; Tue, 1 Jun 2021 13:45:34 +0100 (IST) Received: (qmail 716 invoked from network); 1 Jun 2021 12:45:34 -0000 Received: from unknown (HELO techsingularity.net) (mgorman@techsingularity.net@[84.203.17.255]) by 81.17.254.9 with ESMTPSA (AES256-SHA encrypted, authenticated); 1 Jun 2021 12:45:34 -0000 Date: Tue, 1 Jun 2021 13:45:33 +0100 From: Mel Gorman To: Jesper Dangaard Brouer Cc: Linux-MM , Dave Hansen , Vlastimil Babka , Michal Hocko , LKML , "netdev@vger.kernel.org" Subject: Re: [PATCH 2/2] mm/page_alloc: Allow high-order pages to be stored on the per-cpu lists Message-ID: <20210601124533.GU30378@techsingularity.net> References: <20210531120412.17411-1-mgorman@techsingularity.net> <20210531120412.17411-3-mgorman@techsingularity.net> <20210531172338.2e7cb070@carbon> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20210531172338.2e7cb070@carbon> User-Agent: Mutt/1.10.1 (2018-07-13) X-Rspamd-Queue-Id: D09048019377 Authentication-Results: imf16.hostedemail.com; dkim=none; spf=pass (imf16.hostedemail.com: domain of mgorman@techsingularity.net designates 81.17.249.192 as permitted sender) smtp.mailfrom=mgorman@techsingularity.net; dmarc=none X-Rspamd-Server: rspam03 X-Stat-Signature: 91w9yph3sjskb5oj1ujopihn3u64qdnd X-HE-Tag: 1622551524-909346 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, May 31, 2021 at 05:23:38PM +0200, Jesper Dangaard Brouer wrote: > On Mon, 31 May 2021 13:04:12 +0100 > Mel Gorman wrote: > > > The per-cpu page allocator (PCP) only stores order-0 pages. This means > > that all THP and "cheap" high-order allocations including SLUB contends > > on the zone->lock. This patch extends the PCP allocator to store THP and > > "cheap" high-order pages. Note that struct per_cpu_pages increases in > > size to 256 bytes (4 cache lines) on x86-64. > > > > Note that this is not necessarily a universal performance win because of > > how it is implemented. High-order pages can cause pcp->high to be exceeded > > prematurely for lower-orders so for example, a large number of THP pages > > being freed could release order-0 pages from the PCP lists. Hence, much > > depends on the allocation/free pattern as observed by a single CPU to > > determine if caching helps or hurts a particular workload. > > > > That said, basic performance testing passed. The following is a netperf > > UDP_STREAM test which hits the relevant patches as some of the network > > allocations are high-order. > > This series[1] looks very interesting! I confirm that some network > allocations do use high-order allocations. Thus, I think this will > increase network performance in general, like you confirm below: > Would you be able to do a small test on a real high-speed network? It's something I can do easily myself in a few weeks but I do not have testbed readily available at the moment. It's ok if you do not have the time, it would just be nice if I could include independent results in the changelog if the results are positive. Alternatively, a negative result would mean going back to the drawing board :) -- Mel Gorman SUSE Labs