Messages in this thread | | | Date | Wed, 15 Apr 2020 09:20:01 +0100 | From | Quentin Perret <> | Subject | Re: [PATCH] sched/core: Fix reset-on-fork from RT with uclamp |
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Hi Doug,
On Tuesday 14 Apr 2020 at 13:45:03 (-0700), Doug Anderson wrote: > Hi, > > On Tue, Apr 14, 2020 at 9:13 AM Quentin Perret <qperret@google.com> wrote: > > > > uclamp_fork() resets the uclamp values to their default when the > > reset-on-fork flag is set. It also checks whether the task has a RT > > policy, and sets its uclamp.min to 1024 accordingly. However, during > > reset-on-fork, the task's policy is lowered to SCHED_NORMAL right after, > > hence leading to an erroneous uclamp.min setting for the new task if it > > was forked from RT. > > > > Fix this by removing the unnecessary check on rt_policy() in > > uclamp_fork() as this doesn't make sense if the reset-on-fork flag is > > set. > > > > Reported-by: Chitti Babu Theegala <ctheegal@codeaurora.org> > > Signed-off-by: Quentin Perret <qperret@google.com> > > --- > > kernel/sched/core.c | 4 ---- > > 1 file changed, 4 deletions(-) > > > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > > index 3a61a3b8eaa9..9ea3e484eea2 100644 > > --- a/kernel/sched/core.c > > +++ b/kernel/sched/core.c > > @@ -1234,10 +1234,6 @@ static void uclamp_fork(struct task_struct *p) > > for_each_clamp_id(clamp_id) { > > unsigned int clamp_value = uclamp_none(clamp_id); > > > > - /* By default, RT tasks always get 100% boost */ > > - if (unlikely(rt_task(p) && clamp_id == UCLAMP_MIN)) > > - clamp_value = uclamp_none(UCLAMP_MAX); > > - > > uclamp_se_set(&p->uclamp_req[clamp_id], clamp_value, false); > > The local variable "clamp_value" doesn't have a lot of value anymore, > does it? (Pun intended).
:)
> Remove it?
Right, but I figured the generated code should be similar, and 'uclamp_se_set(&p->uclamp_req[clamp_id], uclamp_none(clamp_id), false);' doesn't fit in 80 cols at this identation level, so I kept the local var. No strong opinion, though.
Thanks, Quentin
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