From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261354AbUKFKf5 (ORCPT ); Sat, 6 Nov 2004 05:35:57 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261360AbUKFKf4 (ORCPT ); Sat, 6 Nov 2004 05:35:56 -0500 Received: from mail06.syd.optusnet.com.au ([211.29.132.187]:27009 "EHLO mail06.syd.optusnet.com.au") by vger.kernel.org with ESMTP id S261354AbUKFKfk (ORCPT ); Sat, 6 Nov 2004 05:35:40 -0500 Message-ID: <418CA8E8.9040506@kolivas.org> Date: Sat, 06 Nov 2004 21:35:20 +1100 From: Con Kolivas User-Agent: Mozilla Thunderbird 0.9 (X11/20041103) X-Accept-Language: en-us, en MIME-Version: 1.0 To: linux Cc: Andrew Morton , Ingo Molnar Subject: [PATCH] [sched-int-changes 3/5] add_requeue_task X-Enigmail-Version: 0.86.1.0 X-Enigmail-Supports: pgp-inline, pgp-mime Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig928DC08AF3A4E04817F8917D" 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) --------------enig928DC08AF3A4E04817F8917D Content-Type: multipart/mixed; boundary="------------010907000808020607080700" This is a multi-part message in MIME format. --------------010907000808020607080700 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit add_requeue_task Please include in at least one -mm release. --------------010907000808020607080700 Content-Type: text/x-patch; name="sched-add_requeue_task.diff" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="sched-add_requeue_task.diff" We can requeue tasks for cheaper then doing a complete dequeue followed by an enqueue. Add the requeue_task function and perform it where possible. This will be hit frequently by upcoming changes to the requeueing in timeslice granularity. Signed-off-by: Con Kolivas Index: linux-2.6.10-rc1-mm3/kernel/sched.c =================================================================== --- linux-2.6.10-rc1-mm3.orig/kernel/sched.c 2004-11-05 20:56:46.608179150 +1100 +++ linux-2.6.10-rc1-mm3/kernel/sched.c 2004-11-05 20:57:14.376900024 +1100 @@ -593,6 +593,15 @@ static void enqueue_task(struct task_str } /* + * Put task to the end of the run list without the overhead of dequeue + * followed by enqueue. + */ +static void requeue_task(struct task_struct *p, prio_array_t *array) +{ + list_move_tail(&p->run_list, array->queue + p->prio); +} + +/* * Used by the migration code - we pull tasks from the head of the * remote queue so we want these tasks to show up at the head of the * local queue: @@ -2456,8 +2465,7 @@ void scheduler_tick(void) set_tsk_need_resched(p); /* put it at the end of the queue: */ - dequeue_task(p, rq->active); - enqueue_task(p, rq->active); + requeue_task(p, rq->active); } goto out_unlock; } @@ -3605,8 +3613,14 @@ asmlinkage long sys_sched_yield(void) } else if (!rq->expired->nr_active) schedstat_inc(rq, yld_exp_empty); - dequeue_task(current, array); - enqueue_task(current, target); + if (array != target) { + dequeue_task(current, array); + enqueue_task(current, target); + } else + /* + * requeue_task is cheaper so perform that if possible. + */ + requeue_task(current, array); /* * Since we are going to call schedule() anyway, there's --------------010907000808020607080700-- --------------enig928DC08AF3A4E04817F8917D Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.6 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org iD8DBQFBjKjoZUg7+tp6mRURApUxAJ0Xt4LHknfe0l5kquYTgGHB1OEqmwCgiZkX 8Ni+z1ZWLmeDPaXrsII9ZTY= =+1Zg -----END PGP SIGNATURE----- --------------enig928DC08AF3A4E04817F8917D--