From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264897AbUGIKEe (ORCPT ); Fri, 9 Jul 2004 06:04:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264819AbUGIKDg (ORCPT ); Fri, 9 Jul 2004 06:03:36 -0400 Received: from mail020.syd.optusnet.com.au ([211.29.132.131]:24739 "EHLO mail020.syd.optusnet.com.au") by vger.kernel.org with ESMTP id S264895AbUGIKA5 (ORCPT ); Fri, 9 Jul 2004 06:00:57 -0400 Message-ID: <40EE6CC2.8070001@kolivas.org> Date: Fri, 09 Jul 2004 20:00:34 +1000 From: Con Kolivas User-Agent: Mozilla Thunderbird 0.7.1 (X11/20040626) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Andrew Morton Cc: Ingo Molnar , Nick Piggin , linux kernel mailing list Subject: Likelihood of rt_tasks X-Enigmail-Version: 0.84.1.0 X-Enigmail-Supports: pgp-inline, pgp-mime Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig8F1C0C58E5451DB09962B8D5" Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig8F1C0C58E5451DB09962B8D5 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit A quick question about the usefulness of making rt_task() checks unlikely in sched-unlikely-rt_task.patch which is in -mm quote: diff -puN include/linux/sched.h~sched-unlikely-rt_task include/linux/sched.h --- 25/include/linux/sched.h~sched-unlikely-rt_task Fri Jul 2 16:33:01 2004 +++ 25-akpm/include/linux/sched.h Fri Jul 2 16:33:01 2004 @@ -300,7 +300,7 @@ struct signal_struct { #define MAX_PRIO (MAX_RT_PRIO + 40) -#define rt_task(p) ((p)->prio < MAX_RT_PRIO) +#define rt_task(p) (unlikely((p)->prio < MAX_RT_PRIO)) /* * Some day this will be a full-fledged user tracking system.. --- While rt tasks are normally unlikely, what happens in the case when you are scheduling one or many running rt_tasks and the majority of your scheduling is rt? Would it be such a good idea in this setting that it is always hitting the slow path of branching all the time? Con --------------enig8F1C0C58E5451DB09962B8D5 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.4 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org iD8DBQFA7mzCZUg7+tp6mRURAh+9AJ9JCt2kDXqQjDAwWfOR44F4meV29gCcC5ks 9WtSZZP40PVI1pJupzXQczk= =k6qO -----END PGP SIGNATURE----- --------------enig8F1C0C58E5451DB09962B8D5--