Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756658Ab0G1Xuu (ORCPT ); Wed, 28 Jul 2010 19:50:50 -0400 Received: from mail-ew0-f46.google.com ([209.85.215.46]:42744 "EHLO mail-ew0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752493Ab0G1Xus (ORCPT ); Wed, 28 Jul 2010 19:50:48 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type; b=x5lUHX9SmCjxrnzHt7IAT50XfrzklcTTt/9YDY/qCtj0yE9P9xj0XhsRafoXomnZQP SgBVDzwwk39akP9M/7t2ZRZOhDNs2hBBjcBXW2210PK23eUI9bHi33KVdY4gIQPjsQdM vyYWqmnlG0Xwq/9AspEDsC4X1eim7PDiCpTPc= MIME-Version: 1.0 In-Reply-To: References: <20100727210210.58d3118c@infradead.org> Date: Wed, 28 Jul 2010 16:50:40 -0700 X-Google-Sender-Auth: Pu__bJS8OGTrYRytzgo0_tNQiAQ Message-ID: Subject: Re: [patch] Remove the per cpu tick skew From: john stultz To: Arjan van de Ven Cc: linux-kernel@vger.kernel.org, tglx@linutronix.de, linux-arch@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1010 Lines: 23 On Wed, Jul 28, 2010 at 1:26 PM, john stultz wrote: > On Tue, Jul 27, 2010 at 9:02 PM, Arjan van de Ven wrote: >> Historically, Linux has tried to make the regular timer tick on the various >> CPUs not happen at the same time, to avoid contention on xtime_lock. >> >> Nowadays, with the tickless kernel, this contention no longer happens >> since time keeping and updating are done differently. In addition, >> this skew is actually hurting power consumption in a measurable >> way on many-core systems. >> > > I'll give it a spin against -rt and see if we show any latency jumps. In my testing on a 8way box, I didn't see any concerning latencies with this patch running cyclictest or a FIFO99 gtod loop. thanks -john -- 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/