From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Tue, 30 Jan 2001 15:52:36 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 30 Jan 2001 15:52:19 -0500 Received: from hq.fsmlabs.com ([209.155.42.197]:58123 "EHLO hq.fsmlabs.com") by vger.kernel.org with ESMTP id ; Tue, 30 Jan 2001 15:52:11 -0500 Date: Tue, 30 Jan 2001 13:51:54 -0700 From: yodaiken@fsmlabs.com To: David Woodhouse Cc: Joe deBlaquiere , yodaiken@fsmlabs.com, Andrew Morton , Nigel Gamble , linux-kernel@vger.kernel.org, linux-audio-dev@ginette.musique.umontreal.ca Subject: Re: [linux-audio-dev] low-latency scheduling patch for 2.4.0 Message-ID: <20010130135154.B27260@hq.fsmlabs.com> In-Reply-To: <3A75A70C.4050205@redhat.com> <200101220150.UAA29623@renoir.op.net> , ; <20010128061428.A21416@hq.fsmlabs.com> <3A742A79.6AF39EEE@uow.edu.au> <3A74462A.80804@redhat.com> <20010129084410.B32652@hq.fsmlabs.com> <3A75A70C.4050205@redhat.com> <30672.980867280@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit X-Mailer: Mutt 0.95.4us In-Reply-To: <30672.980867280@redhat.com>; from David Woodhouse on Tue, Jan 30, 2001 at 03:08:00PM +0000 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org > The thing that really does concern me about the flash driver code is the > fact that it often wants to wait for about 100µs. On machines with > HZ==100, that sucks if you use udelay() and it sucks if you schedule(). So > we end up dropping the spinlock (so at least bottom halves can run again) > and calling: > > static inline void cfi_udelay(int us) > { > if (current->need_resched) > schedule(); > else > udelay(us); > } So then a >100us delay is ok ? I have a dumb RT perspective: either you have to make the deadline or you don't. If you have to make the deadline, then why are you checking need_resched? -- --------------------------------------------------------- Victor Yodaiken Finite State Machine Labs: The RTLinux Company. www.fsmlabs.com www.rtlinux.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/