Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S269243AbUIBWv4 (ORCPT ); Thu, 2 Sep 2004 18:51:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S269234AbUIBWsF (ORCPT ); Thu, 2 Sep 2004 18:48:05 -0400 Received: from omx3-ext.sgi.com ([192.48.171.20]:32149 "EHLO omx3.sgi.com") by vger.kernel.org with ESMTP id S269185AbUIBWq4 (ORCPT ); Thu, 2 Sep 2004 18:46:56 -0400 Date: Thu, 2 Sep 2004 15:42:15 -0700 (PDT) From: Christoph Lameter X-X-Sender: clameter@schroedinger.engr.sgi.com To: john stultz cc: lkml , tim@physik3.uni-rostock.de, george anzinger , albert@users.sourceforge.net, Ulrich.Windl@rz.uni-regensburg.de, Len Brown , linux@dominikbrodowski.de, David Mosberger , Andi Kleen , paulus@samba.org, schwidefsky@de.ibm.com, jimix@us.ibm.com, keith maanthey , greg kh , Patricia Gaughen , Chris McDermott Subject: Re: [RFC][PATCH] new timeofday core subsystem (v.A0) In-Reply-To: <1094164096.14662.345.camel@cog.beaverton.ibm.com> Message-ID: References: <1094159238.14662.318.camel@cog.beaverton.ibm.com> <1094159379.14662.322.camel@cog.beaverton.ibm.com> <1094164096.14662.345.camel@cog.beaverton.ibm.com> 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: 1112 Lines: 26 On Thu, 2 Sep 2004, john stultz wrote: > What about my idea from yesterday of inverting the fastcall > relationship? Instead of creating a structure that exports values and > pointers the fastcall can use to create a time of day, why not use the > fast call to read the raw time and return it back to the time of day > code (which may be running in user context)? This avoids the duplication > of having to re-implement the timeofday/clock_gettime functions in > fastcall asm code. "Read raw time"? How can you read the raw time in a fast call if the fast call needs to do additional function calls (as defined in the proposed time structure) in the kernel context in order to retrieve time? A fast call cannot do any function calls in the kernel context or otherwise. The overhead of the function calls will reduce the performance of time access significantly. - 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/