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 95FF7C2D0DB for ; Mon, 27 Jan 2020 17:33:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7658F22527 for ; Mon, 27 Jan 2020 17:33:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726099AbgA0Rdk (ORCPT ); Mon, 27 Jan 2020 12:33:40 -0500 Received: from mx2.suse.de ([195.135.220.15]:34674 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725828AbgA0Rdk (ORCPT ); Mon, 27 Jan 2020 12:33:40 -0500 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) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --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.) Thanks, Michal --XF85m9dhOBO43t/C Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEEoQaUCWq8F2Id1tNia1+riC5qSgFAl4vHuoACgkQia1+riC5 qSglHw/+OsFYcoJy3FzkbfwtOd2tJfVaDTpasyXswReAFnBRnJmkYbcuaZbFBn6e C98PumV6RYN+Etv7n1RTqxcgj6QCki4kMqNYD758IJqIExsXue9ftCTfwF9iG3CQ DUgppdSbCXdE04oprliEQs7EhY+d6X/Ln5ENZaNTVgXXOjVcAvH5vaiRFfMFyhno +0CsE77seYzs2LjgaS4zcb5FhjhOd3QJ7E0ZdKadnsRpLQ7NqqEsItAOiWBPoqXU 118kbFzjjf84nA7IyH+G34K0XSslmBUzOb3wkjSpTOd6ZuQ3FhPw3Q705PRHrYKM rY8qet8C9/hfHs9Qq/Io/RwZv+2M3J7+DN4o/F4lyZgRb1FNaixZMe4lbGGr6TT3 c9ck2izlt42kT9MqMnHov7qvhI9nkERaCbJ+Xv7BPRRtF/aMH2KYiSucXHRjQh8L 45YOPArLRLzbPYcq/KmDYbCT36yFWrfphOk8iTu2XjjcdXvpcZauAAGJVOyUxDK7 0KL4C9AkkQEhrVs8AI5u6u08jeajbu71R7zopg+2CI34qGco4d63v7hLKxO8CopS N0VUmr+zv6VfPbeGPMPJfsTuZmE6g+14CbKl1DWSdNshlohuyyws5DjruNYEGKvF 59XBuK0JzZ0txSzj5srtLUBtzUwOGdaNS5dJqRXIryV1UpeYPaM= =CZSY -----END PGP SIGNATURE----- --XF85m9dhOBO43t/C--