Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756578AbZJJJZK (ORCPT ); Sat, 10 Oct 2009 05:25:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756257AbZJJJZI (ORCPT ); Sat, 10 Oct 2009 05:25:08 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:42111 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756245AbZJJJZH (ORCPT ); Sat, 10 Oct 2009 05:25:07 -0400 Subject: Re: [PATCH RFC] sched: add notifier for process migration From: Peter Zijlstra To: Avi Kivity Cc: Jeremy Fitzhardinge , Ingo Molnar , Linux Kernel Mailing List , Thomas Gleixner , Andi Kleen , "H. Peter Anvin" In-Reply-To: <4AD04E50.7060001@redhat.com> References: <4ACFA4C5.4020607@goop.org> <1255125738.7439.17.camel@laptop> <4ACFBC98.4070701@goop.org> <1255158863.7866.25.camel@twins> <4AD04E50.7060001@redhat.com> Content-Type: text/plain Content-Transfer-Encoding: 7bit Date: Sat, 10 Oct 2009 11:24:22 +0200 Message-Id: <1255166662.7866.28.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.26.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 890 Lines: 29 On Sat, 2009-10-10 at 11:05 +0200, Avi Kivity wrote: > On 10/10/2009 09:14 AM, Peter Zijlstra wrote: > > Why not do something like: > > > > struct { > > u64 tsc; > > u32 aux; > > } tscp = rdtscp(); > > > > local_time_info = timeinfo[tscp_cpu(tscp)]; > > > > /* yay, consistent tsc and timeinfo !! */ > > > > First, not all processors support rdtscp. Is that a real issue? If its not supported by the early hardware virt chips, tough luck, they sucked anyway :-) > Second, timeinfo might change > at any time due to cpu frequency changes or the entire cpu being > migrated, so we need to loop in any case. Sure. -- 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/