Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752946AbbHZD1L (ORCPT ); Tue, 25 Aug 2015 23:27:11 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:33979 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750737AbbHZD1J (ORCPT ); Tue, 25 Aug 2015 23:27:09 -0400 Date: Tue, 25 Aug 2015 20:27:10 -0700 From: Andrew Morton To: Jason Low Cc: Peter Zijlstra , Ingo Molnar , Thomas Gleixner , Oleg Nesterov , "Paul E. McKenney" , linux-kernel@vger.kernel.org, Frederic Weisbecker , Linus Torvalds , Davidlohr Bueso , Steven Rostedt , Terry Rudd , Rik van Riel , Scott J Norton Subject: Re: [PATCH 0/3] timer: Improve itimers scalability Message-Id: <20150825202710.d960a928.akpm@linux-foundation.org> In-Reply-To: <1440559068-29680-1-git-send-email-jason.low2@hp.com> References: <1440559068-29680-1-git-send-email-jason.low2@hp.com> X-Mailer: Sylpheed 2.7.1 (GTK+ 2.18.9; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1003 Lines: 24 On Tue, 25 Aug 2015 20:17:45 -0700 Jason Low wrote: > When running a database workload on a 16 socket machine, there were > scalability issues related to itimers. > > Commit 1018016c706f addressed the issue with the thread_group_cputimer > spinlock taking up a significant portion of total run time. > > This patch series address the other issue where a lot of time is spent > trying to acquire the sighand lock. It was found in some cases that > 200+ threads were simultaneously contending for the same sighand lock, > reducing throughput by more than 30%. Does this imply that the patchset increased the throughput of this workload by 30%? And is this test case realistic? If not, what are the benefits on a real-world workload? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/