| Message ID | 20240223155749.2958009-1-qyousef@layalina.io (mailing list archive) |
|---|---|
| Headers | show |
| Series | sched: blk: Handle HMP systems when completing IO | expand |
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. > 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(-) >
On Fri, 23 Feb 2024 15:57:47 +0000, 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. > > [...] Applied, thanks! [1/2] sched: Add a new function to compare if two cpus have the same capacity commit: b361c9027b4e4159e7bcca4eb64fd26507c19994 [2/2] block/blk-mq: Don't complete locally if capacities are different commit: af550e4c968294398fc76b075f12d51c76caf753 Best regards,
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(-) > >
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. 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(-)