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 EC8FCC4332F for ; Sat, 4 Nov 2023 03:14:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344511AbjKDDOW (ORCPT ); Fri, 3 Nov 2023 23:14:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55912 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235089AbjKDDOP (ORCPT ); Fri, 3 Nov 2023 23:14:15 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0E232D60 for ; Fri, 3 Nov 2023 20:13:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1699067601; 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; bh=N5kFWH7brXucsVBRzdMRgJtcTW19s76elB4wot7GI30=; b=cqVGQ2doywZMX6vBYGWI28qjqfCaKCa+N4Jqgd7Y7w55DMixHXe75yZRnYLgW10TVQQkPh 5hVV4AK4OcU/tz1t5TEdrOYNTud8PKJohrSdf+FSc7E7J1dM3jZ/tQs44Kwufwci3ne6mE 8Q4RVaWNaWcLcKRQZ4gQHottsWyc8cI= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-114-FHsGKWLoMzyJ9-2FyZjS9A-1; Fri, 03 Nov 2023 23:13:17 -0400 X-MC-Unique: FHsGKWLoMzyJ9-2FyZjS9A-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (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 mimecast-mx02.redhat.com (Postfix) with ESMTPS id 71975811003; Sat, 4 Nov 2023 03:13:17 +0000 (UTC) Received: from llong.com (unknown [10.22.33.74]) by smtp.corp.redhat.com (Postfix) with ESMTP id 8BE49C1290F; Sat, 4 Nov 2023 03:13:16 +0000 (UTC) From: Waiman Long To: Tejun Heo , Zefan Li , Johannes Weiner Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Joe Mario , Sebastian Jug , Yosry Ahmed , Waiman Long Subject: [PATCH v3 0/3] cgroup/rstat: Reduce cpu_lock hold time in cgroup_rstat_flush_locked() Date: Fri, 3 Nov 2023 23:13:00 -0400 Message-Id: <20231104031303.592879-1-longman@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.8 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org v3: - Minor comment twisting as suggested by Yosry. - Add patches 2 and 3 to further reduce lock hold time The purpose of this patch series is to reduce of the cpu_lock hold time in cgroup_rstat_flush_locked() so as to reduce the latency impact when cgroup_rstat_updated() is called as they may contend with each other on the cpu_lock. A parallel kernel build on a 2-socket x86-64 server is used as the benchmarking tool for measuring the lock hold time. Below were the lock hold time frequency distribution before and after applying different number of patches: Hold time Before patch Patch 1 Patches 1-2 Patches 1-3 --------- ------------ ------- ----------- ----------- 0-01 us 804,139 13,738,708 14,594,545 15,484,707 01-05 us 9,772,767 1,177,194 439,926 207,382 05-10 us 4,595,028 4,984 5,960 3,174 10-15 us 303,481 3,562 3,543 3,006 15-20 us 78,971 1,314 1,397 1,066 20-25 us 24,583 18 25 15 25-30 us 6,908 12 12 10 30-40 us 8,015 40-50 us 2,192 50-60 us 316 60-70 us 43 70-80 us 7 80-90 us 2 >90 us 3 Waiman Long (3): cgroup/rstat: Reduce cpu_lock hold time in cgroup_rstat_flush_locked() cgroup/rstat: Optimize cgroup_rstat_updated_list() cgroup: Avoid false cacheline sharing of read mostly rstat_cpu include/linux/cgroup-defs.h | 14 ++++ kernel/cgroup/rstat.c | 129 +++++++++++++++++++++--------------- 2 files changed, 89 insertions(+), 54 deletions(-) -- 2.39.3