From patchwork Thu Sep 20 18:48:05 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Paul E. McKenney" X-Patchwork-Id: 11589 Return-Path: X-Original-To: patchwork@peony.canonical.com Delivered-To: patchwork@peony.canonical.com Received: from fiordland.canonical.com (fiordland.canonical.com [91.189.94.145]) by peony.canonical.com (Postfix) with ESMTP id 1AFA223E54 for ; Thu, 20 Sep 2012 18:48:49 +0000 (UTC) Received: from mail-ie0-f180.google.com (mail-ie0-f180.google.com [209.85.223.180]) by fiordland.canonical.com (Postfix) with ESMTP id 6F07BA1823C for ; Thu, 20 Sep 2012 18:48:48 +0000 (UTC) Received: by ieje10 with SMTP id e10so3420474iej.11 for ; Thu, 20 Sep 2012 11:48:47 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=x-forwarded-to:x-forwarded-for:delivered-to:received-spf:from:to:cc :subject:date:message-id:x-mailer:in-reply-to:references:x-cbid :x-gm-message-state; bh=fz4juxy87PoM8WjzqorDU7cwWMppwIzYjeEMZ3lahJw=; b=LsQ1BEKfY/qcObrYUIrsIPgZxRMdc8AdruDpTORxznaWLKE0bs2h0og69fH1je3f8w vhJZtYBuQjffB7R+gQKCIUHsbQ84DaKa4OshWpLPx02JR8hlbz2W+HQlIAuSBmrKORNR TsFXVTMvvjZcfG4rgbu2KJQquzPlBZAMte98KUExtqU9iMGAm1HQGid3DN+xmX+hzOYe nMBnbVC/CO8C0vI6dwLgQ3Jv7OZ2AE1wSVhoUVzBa0uYJbEp5lY+pLzwIwTAc+xTLsju kqgeMasYY2oCOixa/L8sjdaaisvgW0LgAAtHhuhocNZDQxGEda9Lar9SJpHxgxl3vjeP ad7w== Received: by 10.50.242.3 with SMTP id wm3mr3405964igc.0.1348166927842; Thu, 20 Sep 2012 11:48:47 -0700 (PDT) X-Forwarded-To: linaro-patchwork@canonical.com X-Forwarded-For: patch@linaro.org linaro-patchwork@canonical.com Delivered-To: patches@linaro.org Received: by 10.50.184.232 with SMTP id ex8csp92198igc; Thu, 20 Sep 2012 11:48:47 -0700 (PDT) Received: by 10.43.106.147 with SMTP id du19mr2140078icc.56.1348166927521; Thu, 20 Sep 2012 11:48:47 -0700 (PDT) Received: from e2.ny.us.ibm.com (e2.ny.us.ibm.com. [32.97.182.142]) by mx.google.com with ESMTPS id ls2si25434363igc.67.2012.09.20.11.48.47 (version=TLSv1/SSLv3 cipher=OTHER); Thu, 20 Sep 2012 11:48:47 -0700 (PDT) Received-SPF: pass (google.com: domain of paulmck@linux.vnet.ibm.com designates 32.97.182.142 as permitted sender) client-ip=32.97.182.142; Authentication-Results: mx.google.com; spf=pass (google.com: domain of paulmck@linux.vnet.ibm.com designates 32.97.182.142 as permitted sender) smtp.mail=paulmck@linux.vnet.ibm.com Received: from /spool/local by e2.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 20 Sep 2012 14:48:45 -0400 Received: from d01relay04.pok.ibm.com (9.56.227.236) by e2.ny.us.ibm.com (192.168.1.102) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; Thu, 20 Sep 2012 14:48:44 -0400 Received: from d03av01.boulder.ibm.com (d03av01.boulder.ibm.com [9.17.195.167]) by d01relay04.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q8KImgPw194858 for ; Thu, 20 Sep 2012 14:48:43 -0400 Received: from d03av01.boulder.ibm.com (loopback [127.0.0.1]) by d03av01.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q8KImPOZ020906 for ; Thu, 20 Sep 2012 12:48:35 -0600 Received: from paulmck-ThinkPad-W500 ([9.47.24.72]) by d03av01.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVin) with ESMTP id q8KImNuh020790; Thu, 20 Sep 2012 12:48:24 -0600 Received: by paulmck-ThinkPad-W500 (Postfix, from userid 1000) id 171E3EC52B; Thu, 20 Sep 2012 11:48:22 -0700 (PDT) From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca, josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, Valdis.Kletnieks@vt.edu, dhowells@redhat.com, eric.dumazet@gmail.com, darren@dvhart.com, fweisbec@gmail.com, sbw@mit.edu, patches@linaro.org, Dimitri Sivanich , "Paul E. McKenney" Subject: [PATCH tip/core/rcu 09/23] rcu: Segregate rcu_state fields to improve cache locality Date: Thu, 20 Sep 2012 11:48:05 -0700 Message-Id: <1348166900-18716-9-git-send-email-paulmck@linux.vnet.ibm.com> X-Mailer: git-send-email 1.7.8 In-Reply-To: <1348166900-18716-1-git-send-email-paulmck@linux.vnet.ibm.com> References: <20120920184751.GA18657@linux.vnet.ibm.com> <1348166900-18716-1-git-send-email-paulmck@linux.vnet.ibm.com> x-cbid: 12092018-5112-0000-0000-00000C9996A0 X-Gm-Message-State: ALoCoQkoqz4rXJVJl/tCGXRtFxJejVlLSkyxNEHJt3HFZP+kTH7S2+gTUSLTBhAYTBu4DRujK59W From: Dimitri Sivanich The fields in the rcu_state structure that are protected by the root rcu_node structure's ->lock can share a cache line with the fields protected by ->onofflock. This can result in excessive memory contention on large systems, so this commit applies ____cacheline_internodealigned_in_smp to the ->onofflock field in order to segregate them. Signed-off-by: Dimitri Sivanich Signed-off-by: Paul E. McKenney Tested-by: Dimitri Sivanich Reviewed-by: Josh Triplett --- kernel/rcutree.h | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-) diff --git a/kernel/rcutree.h b/kernel/rcutree.h index effb273..5d92b80 100644 --- a/kernel/rcutree.h +++ b/kernel/rcutree.h @@ -394,7 +394,8 @@ struct rcu_state { /* End of fields guarded by root rcu_node's lock. */ - raw_spinlock_t onofflock; /* exclude on/offline and */ + raw_spinlock_t onofflock ____cacheline_internodealigned_in_smp; + /* exclude on/offline and */ /* starting new GP. */ struct rcu_head *orphan_nxtlist; /* Orphaned callbacks that */ /* need a grace period. */