tree f2fadeb3dbb36f4df2492214c46df2ba32c8eeee
parent 0fcfb00b28c0b7884635dacf38e46d60bf3d4eb1
author Peter Zijlstra <peterz@infradead.org> 1638609242 +0100
committer Peter Zijlstra <peterz@infradead.org> 1638998137 +0100

sched,x86: Don't use cluster topology for x86 hybrid CPUs

For x86 hybrid CPUs like Alder Lake, the order of CPU selection should
be based strictly on CPU priority.  Don't include cluster topology for
hybrid CPUs to avoid interference with such CPU selection order.

On Alder Lake, the Atom CPU cluster has more capacity (4 Atom CPUs) vs
Big core cluster (2 hyperthread CPUs). This could potentially bias CPU
selection towards Atom over Big Core, when Big core CPU has higher
priority.

Fixes: 66558b730f25 ("sched: Add cluster scheduler level for x86")
Suggested-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Tim Chen <tim.c.chen@linux.intel.com>
Tested-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Link: https://lkml.kernel.org/r/20211204091402.GM16608@worktop.programming.kicks-ass.net