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Date: Thu, 11 Nov 2010 15:17:03 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Raistlin <raistlin@...ux.it>
Cc: Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
Steven Rostedt <rostedt@...dmis.org>,
Chris Friesen <cfriesen@...tel.com>, oleg@...hat.com,
Frederic Weisbecker <fweisbec@...il.com>,
Darren Hart <darren@...art.com>,
Johan Eker <johan.eker@...csson.com>,
"p.faure" <p.faure@...tech.ch>,
linux-kernel <linux-kernel@...r.kernel.org>,
Claudio Scordino <claudio@...dence.eu.com>,
michael trimarchi <trimarchi@...is.sssup.it>,
Fabio Checconi <fabio@...dalf.sssup.it>,
Tommaso Cucinotta <cucinotta@...up.it>,
Juri Lelli <juri.lelli@...il.com>,
Nicola Manica <nicola.manica@...i.unitn.it>,
Luca Abeni <luca.abeni@...tn.it>,
Dhaval Giani <dhaval@...is.sssup.it>,
Harald Gustafsson <hgu1972@...il.com>,
paulmck <paulmck@...ux.vnet.ibm.com>
Subject: Re: [RFC][PATCH 05/22] sched: SCHED_DEADLINE policy implementation
On Fri, 2010-10-29 at 08:30 +0200, Raistlin wrote:
> +static void update_curr_dl(struct rq *rq)
> +{
> + struct task_struct *curr = rq->curr;
> + struct sched_dl_entity *dl_se = &curr->dl;
> + u64 delta_exec;
> +
> + if (!dl_task(curr) || !on_dl_rq(dl_se))
> + return;
> +
> + delta_exec = rq->clock - curr->se.exec_start;
> + if (unlikely((s64)delta_exec < 0))
> + delta_exec = 0;
> +
> + schedstat_set(curr->se.statistics.exec_max,
> + max(curr->se.statistics.exec_max, delta_exec));
> +
> + curr->se.sum_exec_runtime += delta_exec;
> + account_group_exec_runtime(curr, delta_exec);
> +
> + curr->se.exec_start = rq->clock;
> + cpuacct_charge(curr, delta_exec);
> +
> + dl_se->runtime -= delta_exec;
> + if (dl_runtime_exceeded(rq, dl_se)) {
> + __dequeue_task_dl(rq, curr, 0);
> + if (likely(start_dl_timer(dl_se)))
> + dl_se->dl_throttled = 1;
> + else
> + enqueue_task_dl(rq, curr, ENQUEUE_REPLENISH);
> +
> + resched_task(curr);
> + }
> +}
So you keep the current task in the rb-tree? If you remove the current
task from the tree you don't have to do the whole dequeue/enqueue thing.
Then again, I guess it only really matters once you push the deadline,
which shouldn't be that often.
Also, you might want to put a conditional around that resched, no point
rescheduling if you're still the leftmost task.
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