Messages in this thread | | | Date | Thu, 3 May 2018 16:12:55 +0100 | From | Morten Rasmussen <> | Subject | Re: [PATCH v8 13/13] arm64: topology: divorce MC scheduling domain from core_siblings |
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On Wed, Apr 25, 2018 at 06:31:21PM -0500, Jeremy Linton wrote: > Now that we have an accurate view of the physical topology > we need to represent it correctly to the scheduler. Generally MC > should equal the LLC in the system, but there are a number of > special cases that need to be dealt with. > > In the case of NUMA in socket, we need to assure that the sched > domain we build for the MC layer isn't larger than the DIE above it. > Similarly for LLC's that might exist in cross socket interconnect or > directory hardware we need to assure that MC is shrunk to the socket > or NUMA node. > > This patch builds a sibling mask for the LLC, and then picks the > smallest of LLC, socket siblings, or NUMA node siblings, which > gives us the behavior described above. This is ever so slightly > different than the similar alternative where we look for a cache > layer less than or equal to the socket/NUMA siblings. > > The logic to pick the MC layer affects all arm64 machines, but > only changes the behavior for DT/MPIDR systems if the NUMA domain > is smaller than the core siblings (generally set to the cluster). > Potentially this fixes a possible bug in DT systems, but really > it only affects ACPI systems where the core siblings is correctly > set to the socket siblings. Thus all currently available ACPI > systems should have MC equal to LLC, including the NUMA in socket > machines where the LLC is partitioned between the NUMA nodes. > > Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
This patch looks good to me.
Acked-by: Morten Rasmussen <morten.rasmussen@arm.com>
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