Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755223AbZIVGfb (ORCPT ); Tue, 22 Sep 2009 02:35:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754941AbZIVGfa (ORCPT ); Tue, 22 Sep 2009 02:35:30 -0400 Received: from netsys.kaist.ac.kr ([143.248.239.50]:37179 "EHLO netsys.kaist.ac.kr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754824AbZIVGfa (ORCPT ); Tue, 22 Sep 2009 02:35:30 -0400 From: "Junhee Lee" To: "'Arjan van de Ven'" , "'Robert Hancock'" Cc: References: <015f01ca3090$85e8a280$91b9e780$@kaist.ac.kr> <4AB673C1.7020909@gmail.com> <20090920203048.7b1b5aa2@infradead.org> In-Reply-To: <20090920203048.7b1b5aa2@infradead.org> Subject: RE: microsecond event scheduling in an application Date: Tue, 22 Sep 2009 15:35:09 +0900 Message-ID: <005601ca3b4e$d5361660$7fa24320$@kaist.ac.kr> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Mailer: Microsoft Office Outlook 12.0 Thread-Index: Aco6IC18ABCMcwY4S8q7GNjooAfm3gBLkaCQ Content-Language: ko Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1739 Lines: 46 Thanks Arjan van de Ven. Your comment is very useful to me. Now I am trying to solve microsecond events scheduling using hrtimer. -----Original Message----- From: Arjan van de Ven [mailto:arjan@infradead.org] Sent: Monday, September 21, 2009 3:31 AM To: Robert Hancock Cc: Junhee Lee; linux-kernel@vger.kernel.org Subject: Re: microsecond event scheduling in an application On Sun, 20 Sep 2009 12:26:09 -0600 Robert Hancock wrote: > On 09/08/2009 08:27 AM, Junhee Lee wrote: > > I am working on event scheduler which handles events in microsecond > > level. Actual this program is a network emulator using simulation > > codes. I'd like to expect that network emulator is working as > > simulation behaviors. Thus high resolution timer interrupt is > > required. But high resolution timer interrupt derived by high tick > > frequency (jiffies clock) must effect the system performance. > > Are there any comments or ways to support microsecond event > > scheduling without performance degradation? > > Just increasing HZ will degrade performance, yes, but we have > hrtimers now which should be able to use granularities smaller than > one jiffy, so it shouldn't be needed.. select/poll use hrtimers, which are jiffies independent.... you'll be hard pressed to notice jiffies granularity in userspace nowadays.. -- Arjan van de Ven Intel Open Source Technology Centre For development, discussion and tips for power savings, visit http://www.lesswatts.org -- 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/