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 A6DA8C54E94 for ; Wed, 25 Jan 2023 07:36:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235091AbjAYHgp (ORCPT ); Wed, 25 Jan 2023 02:36:45 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35734 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235068AbjAYHgk (ORCPT ); Wed, 25 Jan 2023 02:36:40 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CB23337F1E for ; Tue, 24 Jan 2023 23:35:52 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1674632152; 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=KVG76aWPU3FY34u+v28shR/7Qg472WeM1BX+arjDbFU=; b=PFCf9y1aILug4RuXuZ5VVuMIlfN+xTWii3VtkSter+AZ+IHrFtNKfLED+yybJr95iAOI+n GrMhDxUrRoVZrqgcv6kRf4+yLSNAuNniz2DLvBNJK5PUmo0ujYb0RsYMu2s35Qglrzitxu f2TRjQhFlfP6AoDIqpOz1lehtmC8YKo= Received: from mail-oi1-f199.google.com (mail-oi1-f199.google.com [209.85.167.199]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-217-LuheR7CmNoCPHCcc3-3L6g-1; Wed, 25 Jan 2023 02:35:50 -0500 X-MC-Unique: LuheR7CmNoCPHCcc3-3L6g-1 Received: by mail-oi1-f199.google.com with SMTP id j5-20020a056808118500b0036b1cfb4778so5496544oil.2 for ; Tue, 24 Jan 2023 23:35:50 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=KVG76aWPU3FY34u+v28shR/7Qg472WeM1BX+arjDbFU=; b=W/JY/RbRuYTur30xeCwQUThgngLuFDVxA2xcX4abZXR4b2XlKLVxTuBt6gIRlXh9J0 NjJS092Y7i8Dos0EV2axAz1OsjronKI8nMNwXOUA1STiziWWhdFicLqE7zC9iz1mGd+R WqaXaPRYulAmFhZtuCSc+NYiVPzAb8QtDuRnW1a/q7zTIfVAngEda1BGTOo++irDIj2y 8gX7iAyLGzEQEttzCEYutn6eLgFSko0whPNJz52Kr5qrQ5iqtx11l9sqP8JbnTSnUFpL /oPmdRdBaJKCqfLN4qwQCh0CckO7bqVrIepThJIBSQ4vShTxDzwQQ7WXKKM/HIWPFB+A yw7g== X-Gm-Message-State: AFqh2krS9OZeJ5/itAUXxxL4beAIX5IXi7ppZGmOWXjVhiBcEJmmt6rn QtMefceixwOwJeTZvy7HLV9fwZL2GyPTJT8Dd7TBD/S+P4GK2Gi3XLWxBCY7fl4jsN+l5oD61dD OijwGDpoVmfxv6saxA7JDSZ4B X-Received: by 2002:a05:6870:8dc5:b0:15f:74b2:9168 with SMTP id lq5-20020a0568708dc500b0015f74b29168mr14415645oab.4.1674632149720; Tue, 24 Jan 2023 23:35:49 -0800 (PST) X-Google-Smtp-Source: AMrXdXva0ztnWMLaJL80saQFKdei152TK3so9LzytflfDAcnAzjhuVwqsk6VSRdFSyzYlYX+q5Awzg== X-Received: by 2002:a05:6870:8dc5:b0:15f:74b2:9168 with SMTP id lq5-20020a0568708dc500b0015f74b29168mr14415637oab.4.1674632149469; Tue, 24 Jan 2023 23:35:49 -0800 (PST) Received: from LeoBras.redhat.com ([2804:1b3:a800:14fa:9361:c141:6c70:c877]) by smtp.gmail.com with ESMTPSA id x189-20020a4a41c6000000b0050dc79bb80esm1538802ooa.27.2023.01.24.23.35.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 24 Jan 2023 23:35:48 -0800 (PST) From: Leonardo Bras To: Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , Andrew Morton , Marcelo Tosatti Cc: Leonardo Bras , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 1/5] mm/memcontrol: Align percpu memcg_stock to cache Date: Wed, 25 Jan 2023 04:34:58 -0300 Message-Id: <20230125073502.743446-2-leobras@redhat.com> X-Mailer: git-send-email 2.39.1 In-Reply-To: <20230125073502.743446-1-leobras@redhat.com> References: <20230125073502.743446-1-leobras@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When a struct smaller than a cacheline has an instance that is not aligned to cache block size, it could happen that data can be spread across two cachelines. For memcg_stock this could mean the need to fetch and get cache-exclusivity in 2 cachelines instead of 1 when we bounce the cacheline between local cpu functions and drain_all_stock(), which does remote read/write. This could also mean some false-sharing costs being paid due to the cacheline being shared between 2 unrelated structures. Avoid this issue by getting memcg_stock cacheline-aligned. Signed-off-by: Leonardo Bras --- mm/memcontrol.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index ab457f0394ab6..f8e86b88b3c7a 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2188,7 +2188,8 @@ struct memcg_stock_pcp { unsigned long flags; #define FLUSHING_CACHED_CHARGE 0 }; -static DEFINE_PER_CPU(struct memcg_stock_pcp, memcg_stock) = { + +static DEFINE_PER_CPU_SHARED_ALIGNED(struct memcg_stock_pcp, memcg_stock) = { .stock_lock = INIT_LOCAL_LOCK(stock_lock), }; static DEFINE_MUTEX(percpu_charge_mutex); -- 2.39.1 From mboxrd@z Thu Jan 1 00:00:00 1970 From: Leonardo Bras Subject: [PATCH v2 1/5] mm/memcontrol: Align percpu memcg_stock to cache Date: Wed, 25 Jan 2023 04:34:58 -0300 Message-ID: <20230125073502.743446-2-leobras@redhat.com> References: <20230125073502.743446-1-leobras@redhat.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1674632152; 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=KVG76aWPU3FY34u+v28shR/7Qg472WeM1BX+arjDbFU=; b=PFCf9y1aILug4RuXuZ5VVuMIlfN+xTWii3VtkSter+AZ+IHrFtNKfLED+yybJr95iAOI+n GrMhDxUrRoVZrqgcv6kRf4+yLSNAuNniz2DLvBNJK5PUmo0ujYb0RsYMu2s35Qglrzitxu f2TRjQhFlfP6AoDIqpOz1lehtmC8YKo= In-Reply-To: <20230125073502.743446-1-leobras-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> List-ID: Content-Type: text/plain; charset="us-ascii" To: Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , Andrew Morton , Marcelo Tosatti Cc: Leonardo Bras , cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org When a struct smaller than a cacheline has an instance that is not aligned to cache block size, it could happen that data can be spread across two cachelines. For memcg_stock this could mean the need to fetch and get cache-exclusivity in 2 cachelines instead of 1 when we bounce the cacheline between local cpu functions and drain_all_stock(), which does remote read/write. This could also mean some false-sharing costs being paid due to the cacheline being shared between 2 unrelated structures. Avoid this issue by getting memcg_stock cacheline-aligned. Signed-off-by: Leonardo Bras --- mm/memcontrol.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index ab457f0394ab6..f8e86b88b3c7a 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2188,7 +2188,8 @@ struct memcg_stock_pcp { unsigned long flags; #define FLUSHING_CACHED_CHARGE 0 }; -static DEFINE_PER_CPU(struct memcg_stock_pcp, memcg_stock) = { + +static DEFINE_PER_CPU_SHARED_ALIGNED(struct memcg_stock_pcp, memcg_stock) = { .stock_lock = INIT_LOCAL_LOCK(stock_lock), }; static DEFINE_MUTEX(percpu_charge_mutex); -- 2.39.1