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Groups > linux.kernel > #1607861

[RFC v5 4/9] sched/deadline: implement GRUB accounting

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From: Luca Abeni <luca.abeni@santannapisa.it>

According to the GRUB (Greedy Reclaimation of Unused Bandwidth)
reclaiming algorithm, the runtime is not decreased as "dq = -dt",
but as "dq = -Uact dt" (where Uact is the per-runqueue active
utilization).
Hence, this commit modifies the runtime accounting rule in
update_curr_dl() to implement the GRUB rule.

Signed-off-by: Luca Abeni <luca.abeni@santannapisa.it>
Tested-by: Daniel Bristot de Oliveira <bristot@redhat.com>
---
 kernel/sched/deadline.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 238713e..6035311 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -862,6 +862,19 @@ int dl_runtime_exceeded(struct sched_dl_entity *dl_se)
 extern bool sched_rt_bandwidth_account(struct rt_rq *rt_rq);
 
 /*
+ * This function implements the GRUB accounting rule:
+ * according to the GRUB reclaiming algorithm, the runtime is
+ * not decreased as "dq = -dt", but as "dq = -Uact dt", where
+ * Uact is the (per-runqueue) active utilization.
+ * Since rq->dl.running_bw contains Uact * 2^20, the result
+ * has to be shifted right by 20.
+ */
+u64 grub_reclaim(u64 delta, struct rq *rq)
+{
+	return (delta * rq->dl.running_bw) >> 20;
+}
+
+/*
  * Update the current task's runtime statistics (provided it is still
  * a -deadline task and has not been removed from the dl_rq).
  */
@@ -903,6 +916,7 @@ static void update_curr_dl(struct rq *rq)
 
 	sched_rt_avg_update(rq, delta_exec);
 
+	delta_exec = grub_reclaim(delta_exec, rq);
 	dl_se->runtime -= delta_exec;
 
 throttle:
-- 
2.7.4

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[RFC v5 0/9] CPU reclaiming for SCHED_DEADLINE  luca abeni <luca.abeni@santannapisa.it> - 2017-03-23 21:00 +0100
  [RFC v5 8/9] sched/deadline: base GRUB reclaiming on the inactive utilization luca abeni <luca.abeni@santannapisa.it> - 2017-03-23 21:00 +0100
    Re: [RFC v5 8/9] sched/deadline: base GRUB reclaiming on the  inactive utilization Peter Zijlstra <peterz@infradead.org> - 2017-03-27 16:30 +0200
      Re: [RFC v5 8/9] sched/deadline: base GRUB reclaiming on the  inactive utilization Luca Abeni <luca.abeni@santannapisa.it> - 2017-03-27 17:00 +0200
        Re: [RFC v5 8/9] sched/deadline: base GRUB reclaiming on the  inactive utilization Peter Zijlstra <peterz@infradead.org> - 2017-03-27 18:20 +0200
          Re: [RFC v5 8/9] sched/deadline: base GRUB reclaiming on the  inactive utilization luca abeni <luca.abeni@santannapisa.it> - 2017-03-27 19:10 +0200
  [RFC v5 2/9] sched/deadline: improve the tracking of active utilization luca abeni <luca.abeni@santannapisa.it> - 2017-03-23 21:00 +0100
    Re: [RFC v5 2/9] sched/deadline: improve the tracking of active  utilization Peter Zijlstra <peterz@infradead.org> - 2017-03-24 14:30 +0100
    Re: [RFC v5 2/9] sched/deadline: improve the tracking of active  utilization Peter Zijlstra <peterz@infradead.org> - 2017-03-24 14:30 +0100
      Re: [RFC v5 2/9] sched/deadline: improve the tracking of active  utilization luca abeni <luca.abeni@santannapisa.it> - 2017-03-24 22:50 +0100
        Re: [RFC v5 2/9] sched/deadline: improve the tracking of active  utilization Steven Rostedt <rostedt@goodmis.org> - 2017-03-25 03:40 +0100
          Re: [RFC v5 2/9] sched/deadline: improve the tracking of active  utilization Luca Abeni <luca.abeni@santannapisa.it> - 2017-03-27 10:30 +0200
            Re: [RFC v5 2/9] sched/deadline: improve the tracking of active utilization Claudio Scordino <claudio@evidence.eu.com> - 2017-03-27 11:00 +0200
        Re: [RFC v5 2/9] sched/deadline: improve the tracking of active  utilization Juri Lelli <juri.lelli@arm.com> - 2017-03-27 09:20 +0200
          Re: [RFC v5 2/9] sched/deadline: improve the tracking of active  utilization Luca Abeni <luca.abeni@santannapisa.it> - 2017-03-27 10:10 +0200
            Re: [RFC v5 2/9] sched/deadline: improve the tracking of active  utilization Juri Lelli <juri.lelli@arm.com> - 2017-03-27 10:50 +0200
        Re: [RFC v5 2/9] sched/deadline: improve the tracking of active  utilization Luca Abeni <luca.abeni@santannapisa.it> - 2017-03-27 09:40 +0200
    Re: [RFC v5 2/9] sched/deadline: improve the tracking of active utilization Mathieu Poirier <mathieu.poirier@linaro.org> - 2017-03-26 19:40 +0200
      Re: [RFC v5 2/9] sched/deadline: improve the tracking of active  utilization luca abeni <luca.abeni@santannapisa.it> - 2017-03-26 23:10 +0200
  [RFC v5 6/9] sched/deadline: make GRUB a task's flag luca abeni <luca.abeni@santannapisa.it> - 2017-03-23 21:00 +0100
  [RFC v5 7/9] sched/deadline: track the "total rq utilization" too luca abeni <luca.abeni@santannapisa.it> - 2017-03-23 21:00 +0100
  [RFC v5 4/9] sched/deadline: implement GRUB accounting luca abeni <luca.abeni@santannapisa.it> - 2017-03-23 21:00 +0100
  [RFC v5 3/9] sched/deadline: fix the update of the total -deadline utilization luca abeni <luca.abeni@santannapisa.it> - 2017-03-23 21:00 +0100

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