From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S270610AbUKBEQM (ORCPT ); Mon, 1 Nov 2004 23:16:12 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S268465AbUKBEMQ (ORCPT ); Mon, 1 Nov 2004 23:12:16 -0500 Received: from mail15.syd.optusnet.com.au ([211.29.132.196]:26833 "EHLO mail15.syd.optusnet.com.au") by vger.kernel.org with ESMTP id S519239AbUKBEHM (ORCPT ); Mon, 1 Nov 2004 23:07:12 -0500 Message-ID: <418707E5.90705@kolivas.org> Date: Tue, 02 Nov 2004 15:07:01 +1100 From: Con Kolivas User-Agent: Mozilla Thunderbird 0.8 (X11/20040913) X-Accept-Language: en-us, en MIME-Version: 1.0 To: linux Cc: Andrew Morton , Ingo Molnar Subject: [PATCH] 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="------------enigA09E8E700B16A2D07F64E51B" 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) --------------enigA09E8E700B16A2D07F64E51B Content-Type: multipart/mixed; boundary="------------010502000306020307060400" This is a multi-part message in MIME format. --------------010502000306020307060400 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit add requeue task --------------010502000306020307060400 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. Change the granularity code to requeue tasks at their best priority instead of changing priority while they're running. This keeps tasks at their top interactive level during their whole timeslice. Signed-off-by: Con Kolivas Index: linux-2.6.10-rc1-mm2/kernel/sched.c =================================================================== --- linux-2.6.10-rc1-mm2.orig/kernel/sched.c 2004-11-02 14:48:54.686316718 +1100 +++ linux-2.6.10-rc1-mm2/kernel/sched.c 2004-11-02 14:52:51.805763544 +1100 @@ -579,6 +579,16 @@ 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_del(&p->run_list); + list_add_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: @@ -2425,8 +2435,7 @@ 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; } @@ -2467,10 +2476,8 @@ void scheduler_tick(void) (p->time_slice >= TIMESLICE_GRANULARITY(p)) && (p->array == rq->active)) { - dequeue_task(p, rq->active); + requeue_task(p, rq->active); set_tsk_need_resched(p); - p->prio = effective_prio(p); - enqueue_task(p, rq->active); } } out_unlock: @@ -3569,8 +3576,14 @@ 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 --------------010502000306020307060400-- --------------enigA09E8E700B16A2D07F64E51B 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 iD8DBQFBhwfmZUg7+tp6mRURAjTiAKCTA7NYC6c0D7+uLKE3EyDw+GDeCQCgkAB0 DIPJL4mDJnxAT9MoM2T4a4Y= =56ZX -----END PGP SIGNATURE----- --------------enigA09E8E700B16A2D07F64E51B--