From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753146AbZDNFBc (ORCPT ); Tue, 14 Apr 2009 01:01:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751074AbZDNFBV (ORCPT ); Tue, 14 Apr 2009 01:01:21 -0400 Received: from e7.ny.us.ibm.com ([32.97.182.137]:37704 "EHLO e7.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750853AbZDNFBV (ORCPT ); Tue, 14 Apr 2009 01:01:21 -0400 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: anton@samba.org, mingo@elte.hu, akpm@linux-foundation.org, dipankar@in.ibm.com, manfred@colorfullife.com, cl@linux-foundation.org, josht@linux.vnet.ibm.com, schamp@sgi.com, niv@us.ibm.com, dvhltc@us.ibm.com, ego@in.ibm.com, laijs@cn.fujitsu.com, rostedt@goodmis.org, peterz@infradead.org, penberg@cs.helsinki.fi, andi@firstfloor.org, tglx@linutronix.de, "Paul E. McKenney" Subject: [PATCH 0/3] v2 Make hierarchical RCU less IPI-happy and add more tracing Date: Mon, 13 Apr 2009 21:31:15 -0700 Message-Id: <1239683478419-git-send-email-> X-Mailer: git-send-email 1.5.2.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This three-patch set fixes a hierarchical-RCU performance bug located by Anton Blanchard. This bug affects certain high-end floating-point computation-heavy workloads with closely spaced barrier-synchronized iterations, where an interruption of any one CPU's processing during a given iteration slows the system as a whole. This bug manifests itself as excessive resched IPIs, and is strictly a performance regression. It does not affect correctness. The first patch provides the fix for the problem, the second patch adds the tracing, and the third patch adds the documentation for the tracing. Located-by: Anton Blanchard Tested-by: Anton Blanchard Signed-off-by: Paul E. McKenney ---