From patchwork Thu Aug 25 00:05:04 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Shakeel Butt X-Patchwork-Id: 12954098 X-Patchwork-Delegate: kuba@kernel.org 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 19362C04AA5 for ; Thu, 25 Aug 2022 00:05:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230447AbiHYAFc (ORCPT ); Wed, 24 Aug 2022 20:05:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59526 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230414AbiHYAFa (ORCPT ); Wed, 24 Aug 2022 20:05:30 -0400 Received: from mail-pj1-x1049.google.com (mail-pj1-x1049.google.com [IPv6:2607:f8b0:4864:20::1049]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D293065811 for ; Wed, 24 Aug 2022 17:05:28 -0700 (PDT) Received: by mail-pj1-x1049.google.com with SMTP id s10-20020a17090a6e4a00b001fba85daa67so88782pjm.7 for ; Wed, 24 Aug 2022 17:05:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:references:mime-version:message-id:in-reply-to :date:from:to:cc; bh=X0aXbVnjIsqv6IZlugAyzwT5Jn0BIh8DUeidfr3NTwU=; b=pizx5jtbolFH74HPRP+JXhQp2kt4f4Gvo5c8BahsoqOTkDMpUC21gySwAqRyERcsxp RxiJ7ZTDPE4UhNy7ASniRjeSQfLiOp7A52n7UcNJaRcgoNbt5hJSwRUZ2tkpQ2Q3baJ8 4cQTvaVR9bW07R8J1S2oVdOXktAWKIkD5EuCtdCBJ7DOtVg6boyaG97qE7d++5ICk+ah 2bvtXldISERsWobmMdnkvmtae/Ky7rkElbKgMUHUw96nEyyamlUTC7zNBQtNgsfupFiv 1ehcbs9orlmOrXVk8eSGqQ8mVmxBPOLIJjcaHvhtzjRgZpozbsey811NndPtqmQMB85j qK7A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:references:mime-version:message-id:in-reply-to :date:x-gm-message-state:from:to:cc; bh=X0aXbVnjIsqv6IZlugAyzwT5Jn0BIh8DUeidfr3NTwU=; b=38Qmb027aXxsgUzZQaO633GkgCkcIsxiFJK1c767gmYIJLbuTx/+rBx/LMGizSaEnW /teb03yvGZsiW7KxgkjxVCea6XJREn2Rb2TTAw5GGx0atxV1pZ73zxXCIvM6oVKs2mMm orMW9+zoOWBDBzW2XvOJ6TvXgE6UPLXse1vBzrUVzwXLNlRlU5D1KMlsB1vWRnAPL+PQ c+4W/j+treFiJq3GQHy+CdkYGnsQvrZcgOQviWuBFVA1k58lhbEdn1O6uwd50JlD8qRQ B4fuXFeoe89tr3+Kx5b9D63RvaYod9hD2dlq4NGLUgvbLBLz3ZoHKymlbcFuF24t0xPM TPkA== X-Gm-Message-State: ACgBeo02hSGgFoVjbnxFFFuE+7RE8+uVgACjTg1pcIvqCXWSdoIh51CQ JW8l4D6ASKZqhpcvieev2NS3uDFCRWqodQ== X-Google-Smtp-Source: AA6agR5XSREtrswBTLHTLhIxt0y3r3MXI7uBpxQYmDyvEFx98x6p9m1M8gUdoBcShWUI0C8PD7kVrWRRQWbPPw== X-Received: from shakeelb.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:262e]) (user=shakeelb job=sendgmr) by 2002:a05:6a00:4147:b0:52e:2d56:17c8 with SMTP id bv7-20020a056a00414700b0052e2d5617c8mr1426905pfb.51.1661385928246; Wed, 24 Aug 2022 17:05:28 -0700 (PDT) Date: Thu, 25 Aug 2022 00:05:04 +0000 In-Reply-To: <20220825000506.239406-1-shakeelb@google.com> Message-Id: <20220825000506.239406-2-shakeelb@google.com> Mime-Version: 1.0 References: <20220825000506.239406-1-shakeelb@google.com> X-Mailer: git-send-email 2.37.1.595.g718a3a8f04-goog Subject: [PATCH v2 1/3] mm: page_counter: remove unneeded atomic ops for low/min From: Shakeel Butt To: Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song Cc: " =?utf-8?q?Michal_Koutn=C3=BD?= " , Eric Dumazet , Soheil Hassas Yeganeh , Feng Tang , Oliver Sang , Andrew Morton , lkp@lists.01.org, cgroups@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Shakeel Butt Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org For cgroups using low or min protections, the function propagate_protected_usage() was doing an atomic xchg() operation irrespectively. We can optimize out this atomic operation for one specific scenario where the workload is using the protection (i.e. min > 0) and the usage is above the protection (i.e. usage > min). This scenario is actually very common where the users want a part of their workload to be protected against the external reclaim. Though this optimization does introduce a race when the usage is around the protection and concurrent charges and uncharged trip it over or under the protection. In such cases, we might see lower effective protection but the subsequent charge/uncharge will correct it. To evaluate the impact of this optimization, on a 72 CPUs machine, we ran the following workload in a three level of cgroup hierarchy with top level having min and low setup appropriately to see if this optimization is effective for the mentioned case. $ netserver -6 # 36 instances of netperf with following params $ netperf -6 -H ::1 -l 60 -t TCP_SENDFILE -- -m 10K Results (average throughput of netperf): Without (6.0-rc1) 10482.7 Mbps With patch 14542.5 Mbps (38.7% improvement) With the patch, the throughput improved by 38.7% Signed-off-by: Shakeel Butt Reported-by: kernel test robot Acked-by: Soheil Hassas Yeganeh Reviewed-by: Feng Tang Acked-by: Roman Gushchin Acked-by: Michal Hocko --- Changes since v1: - Commit message update with more detail on which scenario is getting optimized and possible race condition. mm/page_counter.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) diff --git a/mm/page_counter.c b/mm/page_counter.c index eb156ff5d603..47711aa28161 100644 --- a/mm/page_counter.c +++ b/mm/page_counter.c @@ -17,24 +17,23 @@ static void propagate_protected_usage(struct page_counter *c, unsigned long usage) { unsigned long protected, old_protected; - unsigned long low, min; long delta; if (!c->parent) return; - min = READ_ONCE(c->min); - if (min || atomic_long_read(&c->min_usage)) { - protected = min(usage, min); + protected = min(usage, READ_ONCE(c->min)); + old_protected = atomic_long_read(&c->min_usage); + if (protected != old_protected) { old_protected = atomic_long_xchg(&c->min_usage, protected); delta = protected - old_protected; if (delta) atomic_long_add(delta, &c->parent->children_min_usage); } - low = READ_ONCE(c->low); - if (low || atomic_long_read(&c->low_usage)) { - protected = min(usage, low); + protected = min(usage, READ_ONCE(c->low)); + old_protected = atomic_long_read(&c->low_usage); + if (protected != old_protected) { old_protected = atomic_long_xchg(&c->low_usage, protected); delta = protected - old_protected; if (delta) From patchwork Thu Aug 25 00:05:05 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Shakeel Butt X-Patchwork-Id: 12954099 X-Patchwork-Delegate: kuba@kernel.org 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 781A0C04AA5 for ; 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Wed, 24 Aug 2022 17:05:33 -0700 (PDT) Date: Thu, 25 Aug 2022 00:05:05 +0000 In-Reply-To: <20220825000506.239406-1-shakeelb@google.com> Message-Id: <20220825000506.239406-3-shakeelb@google.com> Mime-Version: 1.0 References: <20220825000506.239406-1-shakeelb@google.com> X-Mailer: git-send-email 2.37.1.595.g718a3a8f04-goog Subject: [PATCH v2 2/3] mm: page_counter: rearrange struct page_counter fields From: Shakeel Butt To: Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song Cc: " =?utf-8?q?Michal_Koutn=C3=BD?= " , Eric Dumazet , Soheil Hassas Yeganeh , Feng Tang , Oliver Sang , Andrew Morton , lkp@lists.01.org, cgroups@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Shakeel Butt Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org With memcg v2 enabled, memcg->memory.usage is a very hot member for the workloads doing memcg charging on multiple CPUs concurrently. Particularly the network intensive workloads. In addition, there is a false cache sharing between memory.usage and memory.high on the charge path. This patch moves the usage into a separate cacheline and move all the read most fields into separate cacheline. To evaluate the impact of this optimization, on a 72 CPUs machine, we ran the following workload in a three level of cgroup hierarchy. $ netserver -6 # 36 instances of netperf with following params $ netperf -6 -H ::1 -l 60 -t TCP_SENDFILE -- -m 10K Results (average throughput of netperf): Without (6.0-rc1) 10482.7 Mbps With patch 12413.7 Mbps (18.4% improvement) With the patch, the throughput improved by 18.4%. One side-effect of this patch is the increase in the size of struct mem_cgroup. For example with this patch on 64 bit build, the size of struct mem_cgroup increased from 4032 bytes to 4416 bytes. However for the performance improvement, this additional size is worth it. In addition there are opportunities to reduce the size of struct mem_cgroup like deprecation of kmem and tcpmem page counters and better packing. Signed-off-by: Shakeel Butt Reported-by: kernel test robot Reviewed-by: Feng Tang Acked-by: Soheil Hassas Yeganeh Acked-by: Roman Gushchin Acked-by: Michal Hocko --- Changes since v1: - Updated the commit message - Make struct page_counter cache align. include/linux/page_counter.h | 35 +++++++++++++++++++++++------------ 1 file changed, 23 insertions(+), 12 deletions(-) diff --git a/include/linux/page_counter.h b/include/linux/page_counter.h index 679591301994..78a1c934e416 100644 --- a/include/linux/page_counter.h +++ b/include/linux/page_counter.h @@ -3,15 +3,26 @@ #define _LINUX_PAGE_COUNTER_H #include +#include #include #include +#if defined(CONFIG_SMP) +struct pc_padding { + char x[0]; +} ____cacheline_internodealigned_in_smp; +#define PC_PADDING(name) struct pc_padding name +#else +#define PC_PADDING(name) +#endif + struct page_counter { + /* + * Make sure 'usage' does not share cacheline with any other field. The + * memcg->memory.usage is a hot member of struct mem_cgroup. + */ atomic_long_t usage; - unsigned long min; - unsigned long low; - unsigned long high; - unsigned long max; + PC_PADDING(_pad1_); /* effective memory.min and memory.min usage tracking */ unsigned long emin; @@ -23,18 +34,18 @@ struct page_counter { atomic_long_t low_usage; atomic_long_t children_low_usage; - /* legacy */ unsigned long watermark; unsigned long failcnt; - /* - * 'parent' is placed here to be far from 'usage' to reduce - * cache false sharing, as 'usage' is written mostly while - * parent is frequently read for cgroup's hierarchical - * counting nature. - */ + /* Keep all the read most fields in a separete cacheline. */ + PC_PADDING(_pad2_); + + unsigned long min; + unsigned long low; + unsigned long high; + unsigned long max; struct page_counter *parent; -}; +} ____cacheline_internodealigned_in_smp; #if BITS_PER_LONG == 32 #define PAGE_COUNTER_MAX LONG_MAX From patchwork Thu Aug 25 00:05:06 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Shakeel Butt X-Patchwork-Id: 12954100 X-Patchwork-Delegate: kuba@kernel.org 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 4FDDBC04AA5 for ; Thu, 25 Aug 2022 00:05:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230450AbiHYAFv (ORCPT ); Wed, 24 Aug 2022 20:05:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60856 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231150AbiHYAFp (ORCPT ); Wed, 24 Aug 2022 20:05:45 -0400 Received: from mail-pf1-x44a.google.com (mail-pf1-x44a.google.com [IPv6:2607:f8b0:4864:20::44a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B1778696FF for ; Wed, 24 Aug 2022 17:05:39 -0700 (PDT) Received: by mail-pf1-x44a.google.com with SMTP id i3-20020aa78b43000000b005320ac5b724so8087942pfd.4 for ; Wed, 24 Aug 2022 17:05:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:references:mime-version:message-id:in-reply-to :date:from:to:cc; bh=3ANOEI0BBXDszhHsMjNjVkJxW2dSCbobxCznkiQMg0M=; b=M8tSmqMgyZLVy2Ldt7OEwatTGNnYnfDpQ69BuMQNcXOyVDB1zOG1S5rA/96I/PJKxE 4+npbWP3pWJ08Qbrxcia+8i6j7Gu69xnnOJNpGf1qEh/CTh6F27WQ4nVQLW4A9J5Lhh9 wZHGTsioVx7toZiUJ8cHixmiZOFP7E6zdyNZLONxSLuMdImMycE2Fyt+XuqZ+8IhLHsR C6dFsjW4r02bqFmtyRS3Kq6G3VP5sgtlfNBMT7ztQEx6AL13xu9pwUVXfdMd6YEAnByA YGozttZzHIvY64hF0IBSZ5RbI4tZvRxI5hd9vrRa+K0+Wr8X++i6Jrnvoe/mNBWb+0ko v09Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:references:mime-version:message-id:in-reply-to :date:x-gm-message-state:from:to:cc; bh=3ANOEI0BBXDszhHsMjNjVkJxW2dSCbobxCznkiQMg0M=; b=r+W+igIKEcobZs0ep92fUzmwAqE3iLOy3IYq4sIFhDsRFz6CRFVlQMkG0hfKdKPj+7 rNtKVHg/40x6VNyCQmEIbdr7J/YaJ/WBHr28m9baCyxbG6nVLH47WWbtWV3o7X1x8R3C d/NcQuu+j/YlqNVx4+cPOtnzDj6c9qDnlo+aA4NGblcMXMqHD0DOOpD5srSZoXpE5H7Q o9++dC6YP1QrzN85tBk3+NfzgAHzxBGtHJW9u/yvJf+gxTG/biZR6xR0dhfIYJH+c12j qLYLlNSTEWvkrv7+XWV/9Jf16urfOTgx5vPSdwr5RNtkLrIi2Q5N+U60fFTowT0HvjHu Ge2A== X-Gm-Message-State: ACgBeo3GeB+lWiYii00qgTdIm/YTjwAWfXyWXvNpy63EoZ1Y3D3xHGC+ 90NS2/KMw0icpME5AssOwkMwbTHsrFrT0Q== X-Google-Smtp-Source: AA6agR4pbPM00Y2dhBDzDYXIyyPDDsgaDbSO1VcMlYVbQBY5g87vni0ByGdo33smXqzxyN0vznInx5Zn2YarNQ== X-Received: from shakeelb.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:262e]) (user=shakeelb job=sendgmr) by 2002:a05:6a00:1803:b0:536:e9a4:89d4 with SMTP id y3-20020a056a00180300b00536e9a489d4mr1451224pfa.28.1661385939060; Wed, 24 Aug 2022 17:05:39 -0700 (PDT) Date: Thu, 25 Aug 2022 00:05:06 +0000 In-Reply-To: <20220825000506.239406-1-shakeelb@google.com> Message-Id: <20220825000506.239406-4-shakeelb@google.com> Mime-Version: 1.0 References: <20220825000506.239406-1-shakeelb@google.com> X-Mailer: git-send-email 2.37.1.595.g718a3a8f04-goog Subject: [PATCH v2 3/3] memcg: increase MEMCG_CHARGE_BATCH to 64 From: Shakeel Butt To: Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song Cc: " =?utf-8?q?Michal_Koutn=C3=BD?= " , Eric Dumazet , Soheil Hassas Yeganeh , Feng Tang , Oliver Sang , Andrew Morton , lkp@lists.01.org, cgroups@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Shakeel Butt Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org For several years, MEMCG_CHARGE_BATCH was kept at 32 but with bigger machines and the network intensive workloads requiring througput in Gbps, 32 is too small and makes the memcg charging path a bottleneck. For now, increase it to 64 for easy acceptance to 6.0. We will need to revisit this in future for ever increasing demand of higher performance. Please note that the memcg charge path drain the per-cpu memcg charge stock, so there should not be any oom behavior change. Though it does have impact on rstat flushing and high limit reclaim backoff. To evaluate the impact of this optimization, on a 72 CPUs machine, we ran the following workload in a three level of cgroup hierarchy. $ netserver -6 # 36 instances of netperf with following params $ netperf -6 -H ::1 -l 60 -t TCP_SENDFILE -- -m 10K Results (average throughput of netperf): Without (6.0-rc1) 10482.7 Mbps With patch 17064.7 Mbps (62.7% improvement) With the patch, the throughput improved by 62.7%. Signed-off-by: Shakeel Butt Reported-by: kernel test robot Acked-by: Soheil Hassas Yeganeh Reviewed-by: Feng Tang Acked-by: Roman Gushchin Acked-by: Michal Hocko Acked-by: Muchun Song --- Changes since v1: - Updated commit message include/linux/memcontrol.h | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 4d31ce55b1c0..70ae91188e16 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -354,10 +354,11 @@ struct mem_cgroup { }; /* - * size of first charge trial. "32" comes from vmscan.c's magic value. - * TODO: maybe necessary to use big numbers in big irons. + * size of first charge trial. + * TODO: maybe necessary to use big numbers in big irons or dynamic based of the + * workload. */ -#define MEMCG_CHARGE_BATCH 32U +#define MEMCG_CHARGE_BATCH 64U extern struct mem_cgroup *root_mem_cgroup;