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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 8969DC33CB7 for ; Mon, 27 Jan 2020 17:33:42 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 405D7207FD for ; Mon, 27 Jan 2020 17:33:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 405D7207FD Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 841C46B0006; Mon, 27 Jan 2020 12:33:41 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 7F2956B0007; Mon, 27 Jan 2020 12:33:41 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7088A6B0008; Mon, 27 Jan 2020 12:33:41 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0029.hostedemail.com [216.40.44.29]) by kanga.kvack.org (Postfix) with ESMTP id 5AF266B0006 for ; Mon, 27 Jan 2020 12:33:41 -0500 (EST) Received: from smtpin21.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with SMTP id 94A39181AEF15 for ; Mon, 27 Jan 2020 17:33:40 +0000 (UTC) X-FDA: 76424111400.21.shock63_3d1ef3f6ee453 X-HE-Tag: shock63_3d1ef3f6ee453 X-Filterd-Recvd-Size: 3592 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf38.hostedemail.com (Postfix) with ESMTP for ; Mon, 27 Jan 2020 17:33:39 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 50032AC53; Mon, 27 Jan 2020 17:33:38 +0000 (UTC) Date: Mon, 27 Jan 2020 18:33:36 +0100 From: Michal =?iso-8859-1?Q?Koutn=FD?= To: Andrew Morton , Christopher Lameter Cc: Michal Hocko , Christopher Lameter , LKML , linux-mm@kvack.org Subject: Re: SLUB: purpose of sysfs events on cache creation/removal Message-ID: <20200127173336.GB17425@blackbody.suse.cz> References: <20191204153225.GM25242@dhcp22.suse.cz> <20191204173224.GN25242@dhcp22.suse.cz> <20200106115733.GH12699@dhcp22.suse.cz> <20200109145236.GS4951@dhcp22.suse.cz> <20200109114415.cf01bd3ad30c5c4aec981653@linux-foundation.org> <20200117171331.GA17179@blackbody.suse.cz> <20200118161528.94dc18c074aeaa384200486b@linux-foundation.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="XF85m9dhOBO43t/C" Content-Disposition: inline In-Reply-To: <20200118161528.94dc18c074aeaa384200486b@linux-foundation.org> 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: --XF85m9dhOBO43t/C Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Sat, Jan 18, 2020 at 04:15:28PM -0800, Andrew Morton wrote: > > situations, the udev events seem to cause useless tickling of udevd. > > [...] > > and I drew the following ballpark conclusion: > > 1.7% CPU time at 1 event/s -> 60 event/s 100% cpu > Thanks. What effect does this patch have upon these numbers? When I rerun the script with patched kernel, udev sit mostly idle (there were no other udev event sources). So the number can be said to drop to 0% CPU time / event/s. > Typically the author, but not always. If someone else is particularly > motivated to get a patch merged up they can take it over. Christopher, do you consider resending your patch? (I second that it exposes the internal details (wrt cgroup caches) and I can observe the just reading the events by udevd wastes CPU time.) 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