From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760177AbYBXQgB (ORCPT ); Sun, 24 Feb 2008 11:36:01 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759534AbYBXQfs (ORCPT ); Sun, 24 Feb 2008 11:35:48 -0500 Received: from mga03.intel.com ([143.182.124.21]:4338 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759523AbYBXQfr (ORCPT ); Sun, 24 Feb 2008 11:35:47 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.25,398,1199692800"; d="scan'208";a="382933237" Date: Sun, 24 Feb 2008 08:32:29 -0800 From: "Siddha, Suresh B" To: Andi Kleen Cc: Suresh Siddha , mingo@elte.hu, hpa@zytor.com, tglx@linutronix.de, linux-kernel@vger.kernel.org, Arjan van de Ven Subject: Re: [patch 2/2] x86,fpu: lazy allocation of FPU area Message-ID: <20080224163228.GD27194@linux-os.sc.intel.com> References: <20080224023547.264625000@linux-os.sc.intel.com> <20080224023547.412501000@linux-os.sc.intel.com> <20080224122005.GA13637@one.firstfloor.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080224122005.GA13637@one.firstfloor.org> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Feb 24, 2008 at 01:20:05PM +0100, Andi Kleen wrote: > On Sat, Feb 23, 2008 at 06:34:39PM -0800, Suresh Siddha wrote: > > Only allocate the FPU area when the application actually uses FPU, i.e., in the > > first lazy FPU trap. This could save memory for non-fpu using apps. > > Did you measure this making any difference? > > At least at some point glibc always touched the FPU once to initialize > it. Simple kernel boot showed that only 20 or so tasks using FPU, out of 200 or so tasks running. thanks, suresh