Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262730AbVDHHu0 (ORCPT ); Fri, 8 Apr 2005 03:50:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262733AbVDHHu0 (ORCPT ); Fri, 8 Apr 2005 03:50:26 -0400 Received: from terminus.zytor.com ([209.128.68.124]:27621 "EHLO terminus.zytor.com") by vger.kernel.org with ESMTP id S262730AbVDHHt3 (ORCPT ); Fri, 8 Apr 2005 03:49:29 -0400 Message-ID: <42563776.2000207@zytor.com> Date: Fri, 08 Apr 2005 00:49:10 -0700 From: "H. Peter Anvin" User-Agent: Mozilla Thunderbird 1.0.2-1.3.2 (X11/20050324) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Daniel Phillips CC: Rogan Dawes , cw@f00f.org, linux-kernel@vger.kernel.org Subject: Re: Kernel SCM saga.. References: <42562D47.9080705@dawes.za.net> <200504080321.02462.phillips@istop.com> In-Reply-To: <200504080321.02462.phillips@istop.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1393 Lines: 33 Daniel Phillips wrote: > On Friday 08 April 2005 03:05, Rogan Dawes wrote: > >>Take a look at >>http://www.linuxshowcase.org/2001/full_papers/ezolt/ezolt_html/ >> >>Abstract >> >>GNU libc's default setting for malloc can cause a significant >>performance penalty for applications that use it extensively, such as >>Compaq's high performance extended math library, CXML. The default >>malloc tuning can cause a significant number of minor page faults, and >>result in application performance of only half of the true potential. > > > This does not smell like an n*2 suckage, more like n^something suckage. > Finding the elephant under the rug should not be hard. Profile? > Lack of hysteresis can do that, with large swats of memory constantly being claimed and returned to the system. One way to implement hysteresis would be based on a decaying peak-based threshold; unfortunately for optimal performance that requires the C runtime to have a notion of time, and in extreme cases even be able to do asynchronous deallocation, but in reality one can probably assume that the rate of malloc/free is roughly constant over time. -hpa - 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/