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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 165E3C433F5 for ; Thu, 26 May 2022 11:23:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347169AbiEZLXR (ORCPT ); Thu, 26 May 2022 07:23:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48608 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347252AbiEZLW6 (ORCPT ); Thu, 26 May 2022 07:22:58 -0400 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 99FC7273C; Thu, 26 May 2022 04:22:30 -0700 (PDT) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 796581F88B; Thu, 26 May 2022 11:22:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1653564149; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Hv0r7+P52bHUfxGCUQuHehbuy065ANoliNcm3V+0PFI=; b=utAQl6liQ+JUOSurMy22DRK/WHQEwUNAJPY0hO3x8ST/3ghDSYABv66ADrFm/rLcXGZbwL id0nrWLqSv+f/Re52lXyOhtxCSs1Tk51+U/rLpTMsbvmdpGjUFczTfQusPkTjTLUvbjwp2 1JUNuLjIcjQLoyETNXg5L8Htt00NnlQ= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 58D9513AE3; Thu, 26 May 2022 11:22:29 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id NlXVFPVij2LnOgAAMHmgww (envelope-from ); Thu, 26 May 2022 11:22:29 +0000 Date: Thu, 26 May 2022 13:22:28 +0200 From: Michal =?iso-8859-1?Q?Koutn=FD?= To: =?utf-8?B?5Y+y5oCd6L+c?= Cc: Tejun Heo , Li Zefan , Johannes Weiner , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] cgroup: Return if dst_cgrp equals to src_cgrp Message-ID: <20220526112228.GG11007@blackbody.suse.cz> References: <1653066120-21262-1-git-send-email-shisiyuan@xiaomi.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 26, 2022 at 12:40:17PM +0800, 史思远 wrote: > echo 1413 > /dev/cpuset/foreground/cgroup.procs > echo 1413 > /dev/cpuset/foreground/cgroup.procs > echo 1413 > /dev/cpuset/foreground/cgroup.procs Thank you. > In this situation, since the second echo, dst_cgrp equals to src_cgrp(both > cgroups are the 'foreground' cpuset). > cgroup1_procs_write（）-> __cgroup1_procs_write() > -> cgrp = cgroup_kn_lock_live() > -> task = cgroup_procs_write_start(buf...) > -> cgroup_attach_task(cgrp, task, threadgroup); > -> 1) cgroup_migrate_add_src(task_css_set(task), dst_cgrp, &mgctx); // > detect the (src_cgrp == dst_cgrp), don't need to continue the following > migration flow. > -> 2) cgroup_migrate_prepare_dst(&mgctx) Here, I'd like to let you know about [1] > -> 3) cgroup_migrate(leader, threadgroup, &mgctx) > -> 4) cgroup_migrate_finish(&mgctx) // cleanup > -> cgroup_procs_write_finish(); // cleanup > >> The main purpose for this patch is to handle the situation above, and > just noticed that cgroup_update_dfl_csses() also > calls cgroup_migrate_add_src(). So I assume it's a similar situation. We > can discuss more about it. So I think the patch doesn't save that much and identical css_set is better condition to check on (covers cgroup_update_dfl_csses too). Michal [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/kernel/cgroup/cgroup.c?h=v5.18#n2710 From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal =?iso-8859-1?Q?Koutn=FD?= Subject: Re: [PATCH] cgroup: Return if dst_cgrp equals to src_cgrp Date: Thu, 26 May 2022 13:22:28 +0200 Message-ID: <20220526112228.GG11007@blackbody.suse.cz> References: <1653066120-21262-1-git-send-email-shisiyuan@xiaomi.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1653564149; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Hv0r7+P52bHUfxGCUQuHehbuy065ANoliNcm3V+0PFI=; b=utAQl6liQ+JUOSurMy22DRK/WHQEwUNAJPY0hO3x8ST/3ghDSYABv66ADrFm/rLcXGZbwL id0nrWLqSv+f/Re52lXyOhtxCSs1Tk51+U/rLpTMsbvmdpGjUFczTfQusPkTjTLUvbjwp2 1JUNuLjIcjQLoyETNXg5L8Htt00NnlQ= Content-Disposition: inline In-Reply-To: List-ID: Content-Type: text/plain; charset="utf-8" To: =?utf-8?B?5Y+y5oCd6L+c?= Cc: Tejun Heo , Li Zefan , Johannes Weiner , cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org On Thu, May 26, 2022 at 12:40:17PM +0800, 史思远 wrote: > echo 1413 > /dev/cpuset/foreground/cgroup.procs > echo 1413 > /dev/cpuset/foreground/cgroup.procs > echo 1413 > /dev/cpuset/foreground/cgroup.procs Thank you. > In this situation, since the second echo, dst_cgrp equals to src_cgrp(both > cgroups are the 'foreground' cpuset). > cgroup1_procs_write（）-> __cgroup1_procs_write() > -> cgrp = cgroup_kn_lock_live() > -> task = cgroup_procs_write_start(buf...) > -> cgroup_attach_task(cgrp, task, threadgroup); > -> 1) cgroup_migrate_add_src(task_css_set(task), dst_cgrp, &mgctx); // > detect the (src_cgrp == dst_cgrp), don't need to continue the following > migration flow. > -> 2) cgroup_migrate_prepare_dst(&mgctx) Here, I'd like to let you know about [1] > -> 3) cgroup_migrate(leader, threadgroup, &mgctx) > -> 4) cgroup_migrate_finish(&mgctx) // cleanup > -> cgroup_procs_write_finish(); // cleanup > >> The main purpose for this patch is to handle the situation above, and > just noticed that cgroup_update_dfl_csses() also > calls cgroup_migrate_add_src(). So I assume it's a similar situation. We > can discuss more about it. So I think the patch doesn't save that much and identical css_set is better condition to check on (covers cgroup_update_dfl_csses too). Michal [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/kernel/cgroup/cgroup.c?h=v5.18#n2710