On 02/24/24 19:13, Shrikanth Hegde wrote: > > > On 2/23/24 9:27 PM, Qais Yousef wrote: > > Due to recent changes in how topology is represented on asymmetric multi > > processing systems like big.LITTLE where all cpus share the last LLC, there is > > a performance regression as cpus with different compute capacities appear under > > the same LLC and we no longer send an IPI when the requester is running on > > a different cluster with different compute capacity. > > > > Restore the old behavior by adding a new cpus_equal_capacity() function to help > > check for the new condition for these systems. > > > > Changes since v1: > > > > * Split the patch per subsystem. > > * Convert cpus_gte_capacity() to cpus_equal_capacity() > > * Make cpus_equal_capacity() return immediately for SMP systems. > > > > nit: Did you mean !SMP systems here? > Because in changes i see its returning true directly if its in !CONFIG_SMP path. I was referring to this hunk + if (!sched_asym_cpucap_active()) + return true; in cpus_equal_capacity(). In SMP system the condition is always true and there's a static key that tells us if the system is asymmetric. > > > Qais Yousef (2): > > sched: Add a new function to compare if two cpus have the same > > capacity > > block/blk-mq: Don't complete locally if capacities are different > > > > block/blk-mq.c | 5 +++-- > > include/linux/sched/topology.h | 6 ++++++ > > kernel/sched/core.c | 11 +++++++++++ > > 3 files changed, 20 insertions(+), 2 deletions(-) > >
