From patchwork Mon Aug 5 01:30:17 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Waiman Long X-Patchwork-Id: 816888 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0CA5220B0F for ; Mon, 5 Aug 2024 01:31:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722821492; cv=none; b=QDBHaX8rSg0JD+WXMuZkkhlT38BFx6mzLyS4NuykP2Sgmj/IRbBWJHBHY92Zg9/cvDG7zAjKxLzGAqt9kR2CL7keifqDgqbYXv7rhU+Nw4f+WhF4TqS3VE33oT+uCCv8/WehfToF2woM50WqQZUZiPhXbrt7oWOn+utMmyqE0BM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722821492; c=relaxed/simple; bh=mxtcofD8yXEaAR/bV6+10SBjgxhGaO0FQnNefKPZM3g=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=J3at9eOPEn0o4UN3N6WbBZUzxjOCYlYtLlUdyjQt25s6JFWxvuUTAe53J+WWRVMfOMU+FFAFxjQtO6Z9Cer7rdJtQ1SIHDx4BnvogMTiKNbsz/vJkxMjtzwK8jAmTrKJ3fuLwtIDENblF9oodfgbXS1W3lI4lhGGUc7mWsjqzBU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=eZYmu/lS; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="eZYmu/lS" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1722821490; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=N2Qnd3fWt0i6b5mUAj4mng7D982ubzp7a0Vw45AxyrM=; b=eZYmu/lSmc4qvu8C8GrQrbX7y+AFgG7JOUcwc8LJtv9SqB28pTjpvb6qMjp0x57qLaGOJe Yn2ZIyeUHDqCVUs8k7Dj3ah99dwfJYsufN4qn3Bhf2twUdN+nPHwHL46QeJatMAWNVyLio R9XOx+Sdf0CwBbS4eW52HTA/QYCJKlk= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-303-jiT3B-jtOT6E-BAjZNHBrw-1; Sun, 04 Aug 2024 21:30:56 -0400 X-MC-Unique: jiT3B-jtOT6E-BAjZNHBrw-1 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 39266195609F; Mon, 5 Aug 2024 01:30:55 +0000 (UTC) Received: from llong.com (unknown [10.2.16.2]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id CEDC31955E80; Mon, 5 Aug 2024 01:30:52 +0000 (UTC) From: Waiman Long To: Tejun Heo , Zefan Li , Johannes Weiner , =?utf-8?q?Michal_Koutn=C3=BD?= , Shuah Khan Cc: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-kselftest@vger.kernel.org, Chen Ridong , Waiman Long Subject: [PATCH-cgroup 3/5] cgroup/cpuset: Eliminate unncessary sched domains rebuilds in hotplug Date: Sun, 4 Aug 2024 21:30:17 -0400 Message-ID: <20240805013019.724300-4-longman@redhat.com> In-Reply-To: <20240805013019.724300-1-longman@redhat.com> References: <20240805013019.724300-1-longman@redhat.com> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 It was found that some hotplug operations may cause multiple rebuild_sched_domains_locked() calls. Some of those intermediate calls may use cpuset states not in the final correct form leading to incorrect sched domain setting. Fix this problem by using the existing force_rebuild flag to inhibit immediate rebuild_sched_domains_locked() calls if set and only doing one final call at the end. Also renaming the force_rebuild flag to force_sd_rebuild to make its meaning for clear. Signed-off-by: Waiman Long --- kernel/cgroup/cpuset.c | 33 +++++++++++++++++---------------- 1 file changed, 17 insertions(+), 16 deletions(-) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 7287cecb27d1..e070e391d7a8 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -231,6 +231,13 @@ static cpumask_var_t isolated_cpus; /* List of remote partition root children */ static struct list_head remote_children; +/* + * A flag to force sched domain rebuild at the end of an operation while + * inhibiting it in the intermediate stages when set. Currently it is only + * set in hotplug code. + */ +static bool force_sd_rebuild; + /* * Partition root states: * @@ -1467,7 +1474,7 @@ static void update_partition_sd_lb(struct cpuset *cs, int old_prs) clear_bit(CS_SCHED_LOAD_BALANCE, &cs->flags); } - if (rebuild_domains) + if (rebuild_domains && !force_sd_rebuild) rebuild_sched_domains_locked(); } @@ -1820,7 +1827,7 @@ static void remote_partition_check(struct cpuset *cs, struct cpumask *newmask, remote_partition_disable(child, tmp); disable_cnt++; } - if (disable_cnt) + if (disable_cnt && !force_sd_rebuild) rebuild_sched_domains_locked(); } @@ -2425,7 +2432,8 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp, } rcu_read_unlock(); - if (need_rebuild_sched_domains && !(flags & HIER_NO_SD_REBUILD)) + if (need_rebuild_sched_domains && !(flags & HIER_NO_SD_REBUILD) && + !force_sd_rebuild) rebuild_sched_domains_locked(); } @@ -3087,7 +3095,8 @@ static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs, cs->flags = trialcs->flags; spin_unlock_irq(&callback_lock); - if (!cpumask_empty(trialcs->cpus_allowed) && balance_flag_changed) + if (!cpumask_empty(trialcs->cpus_allowed) && balance_flag_changed && + !force_sd_rebuild) rebuild_sched_domains_locked(); if (spread_flag_changed) @@ -4468,11 +4477,9 @@ hotplug_update_tasks(struct cpuset *cs, update_tasks_nodemask(cs); } -static bool force_rebuild; - void cpuset_force_rebuild(void) { - force_rebuild = true; + force_sd_rebuild = true; } /** @@ -4620,15 +4627,9 @@ static void cpuset_handle_hotplug(void) !cpumask_empty(subpartitions_cpus); mems_updated = !nodes_equal(top_cpuset.effective_mems, new_mems); - /* - * In the rare case that hotplug removes all the cpus in - * subpartitions_cpus, we assumed that cpus are updated. - */ - if (!cpus_updated && !cpumask_empty(subpartitions_cpus)) - cpus_updated = true; - /* For v1, synchronize cpus_allowed to cpu_active_mask */ if (cpus_updated) { + cpuset_force_rebuild(); spin_lock_irq(&callback_lock); if (!on_dfl) cpumask_copy(top_cpuset.cpus_allowed, &new_cpus); @@ -4684,8 +4685,8 @@ static void cpuset_handle_hotplug(void) } /* rebuild sched domains if cpus_allowed has changed */ - if (cpus_updated || force_rebuild) { - force_rebuild = false; + if (force_sd_rebuild) { + force_sd_rebuild = false; rebuild_sched_domains_cpuslocked(); }