Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965170AbXBTUpJ (ORCPT ); Tue, 20 Feb 2007 15:45:09 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965153AbXBTUpJ (ORCPT ); Tue, 20 Feb 2007 15:45:09 -0500 Received: from outpost.ds9a.nl ([213.244.168.210]:35585 "EHLO outpost.ds9a.nl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965122AbXBTUpH (ORCPT ); Tue, 20 Feb 2007 15:45:07 -0500 Date: Tue, 20 Feb 2007 21:45:05 +0100 From: bert hubert To: Benjamin LaHaise Cc: Evgeniy Polyakov , Josef Sipek , Andi Kleen , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: all syscalls initially taking 4usec on a P4? Re: nonblocking UDPv4 recvfrom() taking 4usec @ 3GHz? Message-ID: <20070220204505.GB8800@outpost.ds9a.nl> Mail-Followup-To: bert hubert , Benjamin LaHaise , Evgeniy Polyakov , Josef Sipek , Andi Kleen , netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <20070219231447.GA4400@outpost.ds9a.nl> <20070220162714.GA3245@outpost.ds9a.nl> <20070220164124.GA24930@2ka.mipt.ru> <20070220184242.GA30077@filer.fsl.cs.sunysb.edu> <20070220184859.GA1949@2ka.mipt.ru> <20070220193319.GA8800@outpost.ds9a.nl> <20070220194040.GA18976@kvack.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070220194040.GA18976@kvack.org> User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1601 Lines: 46 On Tue, Feb 20, 2007 at 02:40:40PM -0500, Benjamin LaHaise wrote: > Make sure your system is idle. Userspace bloat means that *lots* of idle > activity occurs in between timer ticks on recent distributions -- all those You hit the nail on the head. I had previously measured with X shut down, but the effect didn't disappear. With init=/bin/bash, recvfrom suddenly takes from 900nsec to 1.3usec, with only slight correlation between inter-call delay and cycles spent. I'm investigating this further as it appears this has a real life effect on my P4 - a drastic one! processor : 0 vendor_id : GenuineIntel cpu family : 15 model : 4 model name : Intel(R) Pentium(R) 4 CPU 3.00GHz stepping : 1 cpu MHz : 3000.131 cache size : 1024 KB fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 5 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx constant_tsc pni monitor ds_cpl cid xtpr bogomips : 6003.91 clflush size : 64 Thanks for your help! -- http://www.PowerDNS.com Open source, database driven DNS Software http://netherlabs.nl Open and Closed source services - 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/