Re: [PATCH 0/8] sched/deadline: Return the best satisfying affinity and dl in cpudl_find

From: Byungchul Park
Date: Thu Mar 23 2017 - 18:35:44 EST


On Thu, Mar 23, 2017 at 07:32:35PM +0900, Byungchul Park wrote:
> cpudl_find() is used to find a cpu having the latest dl. The function
> should return the latest cpu among ones satisfying task's affinity and
> dl constraint, but current code gives up immediately and just return
> fail when it fails at the test *only with* the maximum cpu.
>
> For example:
>
> cpu 0 is running a task (dl: 10).
> cpu 1 is running a task (dl: 9).
> cpu 2 is running a task (dl: 8).
> cpu 3 is running a task (dl: 2).
^
should be 1
>
> where cpu 3 want to push a task (affinity is 1 2 3 and dl is 1).
^
should be 2
>
> In this case, the task should be migrated from cpu 3 to cpu 1, and
> preempt cpu 1's task. However, current code just returns fail because
> it fails at the affinity test with the maximum cpu, that is, cpu 0.
>
> This patch set tries to find the best among ones satisfying task's
> affinity and dl constraint until success or no more to see.
>
> Byungchul Park (8):
> sched/deadline: Make find_later_rq() choose a closer cpu in topology
> sched/deadline: Re-define parameters of cpudl heapify functions
> sched/deadline: Add cpudl_maximum_dl() for clean-up
> sched/deadline: Factor out the selecting of suitable max cpu
> sched/deadline: Protect read of cpudl heap with a lock
> sched/deadline: Don't return meaningless cpu in cpudl_maximum_cpu()
> sched/deadline: Factor out the modifying of cpudl's heap tree
> sched/deadline: Return the best satisfying affinity and dl in
> cpudl_find
>
> kernel/sched/cpudeadline.c | 228 +++++++++++++++++++++++++++++++--------------
> kernel/sched/cpudeadline.h | 9 ++
> kernel/sched/deadline.c | 29 +++---
> 3 files changed, 182 insertions(+), 84 deletions(-)
>
> --
> 1.9.1