From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264180AbTFIF3l (ORCPT ); Mon, 9 Jun 2003 01:29:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264181AbTFIF3l (ORCPT ); Mon, 9 Jun 2003 01:29:41 -0400 Received: from franka.aracnet.com ([216.99.193.44]:26557 "EHLO franka.aracnet.com") by vger.kernel.org with ESMTP id S264180AbTFIF3k (ORCPT ); Mon, 9 Jun 2003 01:29:40 -0400 Date: Sun, 08 Jun 2003 22:43:16 -0700 From: "Martin J. Bligh" To: linux-kernel Subject: scheduler interactivity - does this patch help? Message-ID: <36450000.1055137396@[10.10.2.4]> X-Mailer: Mulberry/2.2.1 (Linux/x86) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org I've had this patch (I think from Ingo) kicking around in -mjb for a while. I'm going to drop it unless someone thinks it's useful for some testcase you have ... anyone interested? Thanks, M. diff -urpN -X /home/fletch/.diff.exclude 400-reiserfs_dio/kernel/sched.c 420-sched_interactive/kernel/sched.c --- 400-reiserfs_dio/kernel/sched.c Fri May 30 19:26:34 2003 +++ 420-sched_interactive/kernel/sched.c Fri May 30 19:28:06 2003 @@ -89,6 +89,8 @@ int node_threshold = 125; #define STARVATION_LIMIT (starvation_limit) #define NODE_THRESHOLD (node_threshold) +#define TIMESLICE_GRANULARITY (HZ/20 ?: 1) + /* * If a task is 'interactive' then we reinsert it in the active * array after it has expired its current timeslice. (it will not @@ -1365,6 +1367,27 @@ void scheduler_tick(int user_ticks, int enqueue_task(p, rq->expired); } else enqueue_task(p, rq->active); + } else { + /* + * Prevent a too long timeslice allowing a task to monopolize + * the CPU. We do this by splitting up the timeslice into + * smaller pieces. + * + * Note: this does not mean the task's timeslices expire or + * get lost in any way, they just might be preempted by + * another task of equal priority. (one with higher + * priority would have preempted this task already.) We + * requeue this task to the end of the list on this priority + * level, which is in essence a round-robin of tasks with + * equal priority. + */ + if (!(p->time_slice % TIMESLICE_GRANULARITY) && + (p->array == rq->active)) { + dequeue_task(p, rq->active); + set_tsk_need_resched(p); + p->prio = effective_prio(p); + enqueue_task(p, rq->active); + } } out_unlock: spin_unlock(&rq->lock);