Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752650Ab2BQOQp (ORCPT ); Fri, 17 Feb 2012 09:16:45 -0500 Received: from relay3.sgi.com ([192.48.152.1]:50309 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751862Ab2BQOQo (ORCPT ); Fri, 17 Feb 2012 09:16:44 -0500 Date: Fri, 17 Feb 2012 08:16:41 -0600 From: Dimitri Sivanich To: Ingo Molnar Cc: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , John Stultz , x86@kernel.org, linux-kernel@vger.kernel.org, Jack Steiner Subject: Re: [PATCH] x86 uv: lower UV rtc clocksource rating Message-ID: <20120217141641.GA28063@sgi.com> References: <20120216201042.GA10260@sgi.com> <20120217120242.GC25601@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120217120242.GC25601@elte.hu> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1812 Lines: 52 On Fri, Feb 17, 2012 at 01:02:42PM +0100, Ingo Molnar wrote: > > * Dimitri Sivanich wrote: > > > Lower the rating of the UV rtc clocksource to just below that of the tsc. > > This changelog is deficient for obvious reasons, mind updating > it? > OK. Is this sufficient? Lower the rating of the UV rtc clocksource to just below that of the tsc. Reading the tsc clocksource has lower latency than reading the rtc, so favor it in situations where it is synchronized and stable. When the tsc is unsynchronized, the rtc needs to be the chosen clocksource. Signed-off-by: Dimitri Sivanich --- arch/x86/platform/uv/uv_time.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) Index: linux/arch/x86/platform/uv/uv_time.c =================================================================== --- linux.orig/arch/x86/platform/uv/uv_time.c +++ linux/arch/x86/platform/uv/uv_time.c @@ -37,7 +37,7 @@ static void uv_rtc_timer_setup(enum cloc static struct clocksource clocksource_uv = { .name = RTC_NAME, - .rating = 400, + .rating = 299, .read = uv_read_rtc, .mask = (cycle_t)UVH_RTC_REAL_TIME_CLOCK_MASK, .flags = CLOCK_SOURCE_IS_CONTINUOUS, @@ -379,10 +379,6 @@ static __init int uv_rtc_setup_clock(voi if (!is_uv_system()) return -ENODEV; - /* If single blade, prefer tsc */ - if (uv_num_possible_blades() == 1) - clocksource_uv.rating = 250; - rc = clocksource_register_hz(&clocksource_uv, sn_rtc_cycles_per_second); if (rc) printk(KERN_INFO "UV RTC clocksource failed rc %d\n", rc); -- 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/