Messages in this thread |  | | Date | Mon, 25 Nov 2019 16:36:50 -0500 | From | Steven Rostedt <> | Subject | Re: [PATCH v2] sched: rt: Make RT capacity aware |
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Sorry for the very late response...
On Wed, 9 Oct 2019 11:46:11 +0100 Qais Yousef <qais.yousef@arm.com> wrote:
> ATM the uclamp value are only used for frequency selection; but on > heterogeneous systems this is not enough and we need to ensure that the > capacity of the CPU is >= uclamp_min. Which is what implemented here.
Is it possible that the capacity can be fixed, where the process can just have a cpu mask of CPUs that has the capacity for it?
Not that this will affect this patch now, but just something for the future.
> > capacity_orig_of(cpu) >= rt_task.uclamp_min > > Note that by default uclamp.min is 1024, which means that RT tasks will > always be biased towards the big CPUs, which make for a better more > predictable behavior for the default case. > > Must stress that the bias acts as a hint rather than a definite > placement strategy. For example, if all big cores are busy executing > other RT tasks we can't guarantee that a new RT task will be placed > there. > > On non-heterogeneous systems the original behavior of RT should be > retained. Similarly if uclamp is not selected in the config. > > Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
-- Steve
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