lkml.org 
[lkml]   [2024]   [Feb]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v2 0/2] sched: blk: Handle HMP systems when completing IO
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(-)
> >

\
 
 \ /
  Last update: 2024-05-27 15:20    [W:0.089 / U:0.284 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site