From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751924Ab1IWT3h (ORCPT ); Fri, 23 Sep 2011 15:29:37 -0400 Received: from mga09.intel.com ([134.134.136.24]:29006 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751546Ab1IWT3g (ORCPT ); Fri, 23 Sep 2011 15:29:36 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.67,352,1309762800"; d="scan'208";a="55309854" Message-ID: <4E7CDE1F.90004@linux.intel.com> Date: Fri, 23 Sep 2011 12:29:35 -0700 From: Arjan van de Ven User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:6.0.2) Gecko/20110902 Thunderbird/6.0.2 MIME-Version: 1.0 To: Venkatesh Pallipadi CC: Thomas Gleixner , Peter Zijlstra , Ingo Molnar , Suresh Siddha , linux-kernel@vger.kernel.org Subject: Re: [RFC] Introduce greedy hrtimer walk on idle References: <1316804080-6396-1-git-send-email-venki@google.com> In-Reply-To: <1316804080-6396-1-git-send-email-venki@google.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/23/2011 11:54 AM, Venkatesh Pallipadi wrote: > Current hrtimer range timers reduces the number of timer interrupts by > grouping together softexpired timers until the next unexpired timer. > It does not look at softexpired timers that may be after the unexpired > timer in the rbtree. > > Specifically, as the comment in hrtimer.c says > * The immediate goal for using the softexpires is > * minimizing wakeups, not running timers at the > * earliest interrupt after their soft expiration. > * This allows us to avoid using a Priority Search > * Tree, which can answer a stabbing querry for > * overlapping intervals and instead use the simple > * BST we already have. > * We don't add extra wakeups by delaying timers that > * are right-of a not yet expired timer, because that > * timer will have to trigger a wakeup anyway. > Since you found that it now makes a difference, I'm all for it.. Acked-by: Arjan van de Ven (at original introduction it was in the noise, but usage patterns clearly changed a lot and ranges are much more prevalent now) I would not do the sysctl/configurability thing though.... that's not worth it.