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 97470C433DB for ; Thu, 25 Mar 2021 13:26:02 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 20B9461A17 for ; Thu, 25 Mar 2021 13:26:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 20B9461A17 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 9F8316B006C; Thu, 25 Mar 2021 09:26:01 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 9A8436B0070; Thu, 25 Mar 2021 09:26:01 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 848AF6B0071; Thu, 25 Mar 2021 09:26:01 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0234.hostedemail.com [216.40.44.234]) by kanga.kvack.org (Postfix) with ESMTP id 6B3E66B006C for ; Thu, 25 Mar 2021 09:26:01 -0400 (EDT) Received: from smtpin06.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 1E2D9184DB444 for ; Thu, 25 Mar 2021 13:26:01 +0000 (UTC) X-FDA: 77958469722.06.8DD74E9 Received: from outbound-smtp31.blacknight.com (outbound-smtp31.blacknight.com [81.17.249.62]) by imf18.hostedemail.com (Postfix) with ESMTP id A72BA2000241 for ; Thu, 25 Mar 2021 13:25:59 +0000 (UTC) Received: from mail.blacknight.com (pemlinmail04.blacknight.ie [81.17.254.17]) by outbound-smtp31.blacknight.com (Postfix) with ESMTPS id 63464C0B17 for ; Thu, 25 Mar 2021 13:25:58 +0000 (GMT) Received: (qmail 25209 invoked from network); 25 Mar 2021 13:25:58 -0000 Received: from unknown (HELO techsingularity.net) (mgorman@techsingularity.net@[84.203.22.4]) by 81.17.254.9 with ESMTPSA (AES256-SHA encrypted, authenticated); 25 Mar 2021 13:25:58 -0000 Date: Thu, 25 Mar 2021 13:25:56 +0000 From: Mel Gorman To: Matthew Wilcox Cc: Andrew Morton , Uladzislau Rezki , Chuck Lever , Jesper Dangaard Brouer , Christoph Hellwig , Alexander Duyck , Vlastimil Babka , Ilias Apalodimas , LKML , Linux-Net , Linux-MM , Linux-NFS Subject: Re: [PATCH 0/9 v6] Introduce a bulk order-0 page allocator with two in-tree users Message-ID: <20210325132556.GS3697@techsingularity.net> References: <20210325114228.27719-1-mgorman@techsingularity.net> <20210325125001.GW1719932@casper.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20210325125001.GW1719932@casper.infradead.org> User-Agent: Mutt/1.10.1 (2018-07-13) X-Stat-Signature: p1c5r7dmm5ebio4sb6kso8r3k87o5c8m X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: A72BA2000241 Received-SPF: none (techsingularity.net>: No applicable sender policy available) receiver=imf18; identity=mailfrom; envelope-from=""; helo=outbound-smtp31.blacknight.com; client-ip=81.17.249.62 X-HE-DKIM-Result: none/none X-HE-Tag: 1616678759-396529 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 Thu, Mar 25, 2021 at 12:50:01PM +0000, Matthew Wilcox wrote: > On Thu, Mar 25, 2021 at 11:42:19AM +0000, Mel Gorman wrote: > > This series introduces a bulk order-0 page allocator with sunrpc and > > the network page pool being the first users. The implementation is not > > efficient as semantics needed to be ironed out first. If no other semantic > > changes are needed, it can be made more efficient. Despite that, this > > is a performance-related for users that require multiple pages for an > > operation without multiple round-trips to the page allocator. Quoting > > the last patch for the high-speed networking use-case > > > > Kernel XDP stats CPU pps Delta > > Baseline XDP-RX CPU total 3,771,046 n/a > > List XDP-RX CPU total 3,940,242 +4.49% > > Array XDP-RX CPU total 4,249,224 +12.68% > > > > >From the SUNRPC traces of svc_alloc_arg() > > > > Single page: 25.007 us per call over 532,571 calls > > Bulk list: 6.258 us per call over 517,034 calls > > Bulk array: 4.590 us per call over 517,442 calls > > > > Both potential users in this series are corner cases (NFS and high-speed > > networks) so it is unlikely that most users will see any benefit in the > > short term. Other potential other users are batch allocations for page > > cache readahead, fault around and SLUB allocations when high-order pages > > are unavailable. It's unknown how much benefit would be seen by converting > > multiple page allocation calls to a single batch or what difference it may > > make to headline performance. > > We have a third user, vmalloc(), with a 16% perf improvement. I know the > email says 21% but that includes the 5% improvement from switching to > kvmalloc() to allocate area->pages. > > https://lore.kernel.org/linux-mm/20210323133948.GA10046@pc638.lan/ > That's fairly promising. Assuming the bulk allocator gets merged, it would make sense to add vmalloc on top. That's for bringing it to my attention because it's far more relevant than my imaginary potential use cases. > I don't know how many _frequent_ vmalloc users we have that will benefit > from this, but it's probably more than will benefit from improvements > to 200Gbit networking performance. I think it was 100Gbit being looked at but your point is still valid and there is no harm in incrementally improving over time. -- Mel Gorman SUSE Labs