From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754559AbYIDPqe (ORCPT ); Thu, 4 Sep 2008 11:46:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751472AbYIDPq1 (ORCPT ); Thu, 4 Sep 2008 11:46:27 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:37283 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751002AbYIDPq0 (ORCPT ); Thu, 4 Sep 2008 11:46:26 -0400 Date: Thu, 4 Sep 2008 08:45:59 -0700 (PDT) From: Linus Torvalds To: Ingo Molnar cc: Thomas Gleixner , LKML , Alok Kataria , Arjan van de Veen , "H. Peter Anvin" Subject: Re: [RFC patch 0/4] TSC calibration improvements In-Reply-To: <20080904153620.GC7120@elte.hu> Message-ID: References: <20080904150339.896115280@linutronix.de> <20080904153620.GC7120@elte.hu> User-Agent: Alpine 1.10 (LFD 962 2008-03-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 4 Sep 2008, Ingo Molnar wrote: > > i've added them to tip/x86/tsc and merged it into tip/master - if > there's test success we can merge it into x86/urgent as well and push it > into v2.6.27. Any objections to that merge route? I don't think it's quite that urgent, and wonder what the downside is of just changing the timeout to 10ms. On 32-bit x86, it was 30ms (I think) before the merge, so it sounds like 50ms was a bit excessive even before the whole "loop five times"/ So _short_ term, I'd really prefer (a) looping just three times and (b) looping with a smaller timeout. Long-term, I actually think even 10ms is actually a total waste. I'll post my trial "quick calibration" code that is more likely to fail under virtualization or SMM (or, indeed, perhaps even on things like TMTA CPU's that can have longer latencies due to translation), but that is really fast and knows very intimately when it succeeds. I just need to do slightly more testing. Linus