Re: [Announce] [patch] Modular Scheduler Core and Completely Fair Scheduler [CFS]

[Ingo Molnar]

* Nick Piggin <npiggin@xxxxxxx> wrote:

> >    The CFS patch uses a completely different approach and implementation
> >    from RSDL/SD. My goal was to make CFS's interactivity quality exceed
> >    that of RSDL/SD, which is a high standard to meet :-) Testing
> >    feedback is welcome to decide this one way or another. [ and, in any
> >    case, all of SD's logic could be added via a kernel/sched_sd.c module
> >    as well, if Con is interested in such an approach. ]
> 
> Comment about the code: shouldn't you be requeueing the task in the 
> rbtree wherever you change wait_runtime? eg. task_new_fair? [...]

yes: the task's position within the rbtree is updated every time 
wherever wait_runtime is change. task_new_fair is the method during new 
task creation, but indeed i forgot to requeue the parent. I've fixed 
this in my tree (see the delta patch below) - thanks!

	Ingo

----------->
From: Ingo Molnar <mingo@xxxxxxx>
Subject: [cfs] fix parent's rbtree position

Nick noticed that upon fork we change parent->wait_runtime but we do not 
requeue it within the rbtree.

Signed-off-by: Ingo Molnar <mingo@xxxxxxx>

Index: linux/kernel/sched_fair.c
===================================================================
--- linux.orig/kernel/sched_fair.c
+++ linux/kernel/sched_fair.c
@@ -524,6 +524,8 @@ static void task_new_fair(struct rq *rq,
 
 	p->wait_runtime = parent->wait_runtime/2;
 	parent->wait_runtime /= 2;
+	requeue_task_fair(rq, parent);
+
 	/*
 	 * For the first timeslice we allow child threads
 	 * to move their parent-inherited fairness back
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/