From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Gleixner Subject: Re: [take12 3/3] kevent: Timer notifications. Date: Mon, 21 Aug 2006 16:25:49 +0200 Message-ID: <1156170349.4725.29.camel@localhost.localdomain> References: <11561555893621@2ka.mipt.ru> <1156155589287@2ka.mipt.ru> <20060821111239.GA30945@infradead.org> <20060821111848.GB8608@2ka.mipt.ru> Reply-To: tglx@linutronix.de Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: Christoph Hellwig , lkml , David Miller , Ulrich Drepper , Andrew Morton , netdev , Zach Brown Return-path: Received: from www.osadl.org ([213.239.205.134]:9112 "EHLO mail.tglx.de") by vger.kernel.org with ESMTP id S932187AbWHVRCZ (ORCPT ); Tue, 22 Aug 2006 13:02:25 -0400 To: Evgeniy Polyakov In-Reply-To: <20060821111848.GB8608@2ka.mipt.ru> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Mon, 2006-08-21 at 15:18 +0400, Evgeniy Polyakov wrote: > On Mon, Aug 21, 2006 at 12:12:39PM +0100, Christoph Hellwig (hch@infradead.org) wrote: > > On Mon, Aug 21, 2006 at 02:19:49PM +0400, Evgeniy Polyakov wrote: > > > > > > > > > Timer notifications. > > > > > > Timer notifications can be used for fine grained per-process time > > > management, since interval timers are very inconvenient to use, > > > and they are limited. > > > Shouldn't this at leat use a hrtimer? > > Not everymachine has them Every machine has hrtimers - not necessarily with high resolution timer support, but the core code is there in any case and it is designed to provide fine grained timers. In case of high resolution time support one would expect that the "fine grained" timer event is actually fine grained. > and getting into account possibility that > userspace can be scheduled away, it will be overkill. If you think out your argument then everything which is fine grained or high responsive should be removed from userspace access for the very same reason. Please look at the existing users of the hrtimer subsystem - all of them are exposed to userspace. tglx