Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263221AbVCKHO2 (ORCPT ); Fri, 11 Mar 2005 02:14:28 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263223AbVCKHO2 (ORCPT ); Fri, 11 Mar 2005 02:14:28 -0500 Received: from one.firstfloor.org ([213.235.205.2]:18345 "EHLO one.firstfloor.org") by vger.kernel.org with ESMTP id S263221AbVCKHO0 (ORCPT ); Fri, 11 Mar 2005 02:14:26 -0500 To: Andrew Morton Cc: linux-kernel@vger.kernel.org, peterc@gelato.unsw.edu.au Subject: Re: Microstate Accounting for 2.6.11 References: <16945.5058.251259.828855@berry.gelato.unsw.EDU.AU> <20050310200808.306caf98.akpm@osdl.org> From: Andi Kleen Date: Fri, 11 Mar 2005 08:14:25 +0100 In-Reply-To: <20050310200808.306caf98.akpm@osdl.org> (Andrew Morton's message of "Thu, 10 Mar 2005 20:08:08 -0800") Message-ID: User-Agent: Gnus/5.110002 (No Gnus v0.2) Emacs/21.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 606 Lines: 17 Andrew Morton writes: > Why does the kernel need this feature? > > Have you any numbers on the overhead? It does RDTSC and lots of complicated stuff twice for each system call. On P4 this will be extremly slow (> 1000cycles combined) It is pretty unlikely that whatever it does justifies this extreme overhead in a critical fast path. -Andi - 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/