Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966889Ab2EOVIq (ORCPT ); Tue, 15 May 2012 17:08:46 -0400 Received: from mail-vb0-f46.google.com ([209.85.212.46]:61400 "EHLO mail-vb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966814Ab2EOVIn convert rfc822-to-8bit (ORCPT ); Tue, 15 May 2012 17:08:43 -0400 MIME-Version: 1.0 In-Reply-To: <4FA17F6A.9000606@genband.com> References: <4FA17F6A.9000606@genband.com> Date: Tue, 15 May 2012 14:08:42 -0700 X-Google-Sender-Auth: g_O2Zx9wQ71HPx5e6xA8hqV-K94 Message-ID: Subject: Re: read() syscall slowing down due to other threads? From: George Porter To: Chris Friesen Cc: linux-kernel@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1563 Lines: 42 Thanks for the response--we did play around with core affinity, and it does make a difference for sure. The major thing was turning off HP's power management stuff, and putting the BIOS into high-performance mode. That helped a lot. Thanks, George On Wed, May 2, 2012 at 11:39 AM, Chris Friesen wrote: > On 05/01/2012 12:03 AM, George Porter wrote: > >> However, if I start doing more computation on those other threads, the >> read() syscalls take longer to read the same amount of data, >> eventually slowing down to 50 MBps (50% slower). ?I've used >> setaffinity() to isolate the Reader threads to one set of cores, and >> the compute threads to a different set of cores, and so I don't think >> it is CPU/scheduling interference. >> >> Thoughts? ?Has anyone run into this before? > > > If you're using hyperthreading you may want to try it with either putting > the computation threads on the siblings of the cpus for the reader threads > (to share cache) or else not on the siblings of the cpus for the reader > threads (to minimize contention of cpu resources). > > Similarly, you may want to play with wither or not the threads are on the > same or different sockets. > > Chris > > -- > Chris Friesen > Software Developer > GENBAND > chris.friesen@genband.com > www.genband.com -- 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/