Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261224AbUKHUwc (ORCPT ); Mon, 8 Nov 2004 15:52:32 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261222AbUKHUvO (ORCPT ); Mon, 8 Nov 2004 15:51:14 -0500 Received: from hqemgate00.nvidia.com ([216.228.112.144]:37900 "EHLO hqemgate00.nvidia.com") by vger.kernel.org with ESMTP id S261221AbUKHUuk convert rfc822-to-8bit (ORCPT ); Mon, 8 Nov 2004 15:50:40 -0500 X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 Content-class: urn:content-classes:message MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT Subject: RE: SCHED_RR and kernel threads Date: Mon, 8 Nov 2004 12:50:37 -0800 Message-ID: X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: SCHED_RR and kernel threads thread-index: AcTF0bc08eaHc3fvSzq0CPrcc4168QAAiQRg From: "Stephen Warren" To: "Con Kolivas" Cc: X-OriginalArrivalTime: 08 Nov 2004 20:50:38.0983 (UTC) FILETIME=[9A8C2170:01C4C5D4] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1643 Lines: 38 > From: Con Kolivas [mailto:kernel@kolivas.org] > Stephen Warren wrote: > > It appears that during times of high application CPU usage, some > > *kernel* threads don't get to run. > > ... > > This appears to be due to the fact that the kernel threads are all > > SCHED_OTHER, so our SCHED_RR user-space application trumps them! > > Don't run your userspace at SCHED_RR? The kernel threads are > SCHED_NORMAL precisely for the reason that you wont get real time > performance if the kernel threads rear their ugly heads, > albeit rarely. We have actually set the kernel threads to priority SCHED_RR 50, and most user-space threads to SCHED_RR priority 50. Some critical user-space threads are above priority 50. Won't this allow the kernel and user space threads to co-operate nicely all the time? What is it specifically that will make kernel SCHED_RR threads cause non-real-time operation? If it's just a bunch of corner cases or odd conditions, we may be in an environment we can control so that doesn't happen... I guess we could have most threads stay at SCHED_NORMAL, and just make the few critical threads SCHED_RR, but I'm getting a lot of push-back on this, since it makes our thread API a lot more complex. -- Stephen Warren, Software Engineer, NVIDIA, Fort Collins, CO swarren@nvidia.com http://www.nvidia.com/ swarren@wwwdotorg.org http://www.wwwdotorg.org/pgp.html - 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/