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SubjectRe: [RFC PATCH] sched: Introduce per-mm/cpu concurrency id state
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On 2023-03-31 04:52, Aaron Lu wrote:
> On Thu, Mar 30, 2023 at 07:09:11PM -0400, Mathieu Desnoyers wrote:
>> Keep track of the currently allocated mm_cid for each mm/cpu rather than
>> freeing them immediately. This eliminates most atomic ops when context
>> switching back and forth between threads belonging to different memory
>> spaces in multi-threaded scenarios (many processes, each with many
>> threads).
>
> Good news, the lock contention is now gone and back to v6.2 level:

Hi Aaron,

Can you please test the updated patch I've sent ? I have updated the
subject to make it clear that this is a fix for a performance regression,
improved comments, and it now passes more thorough testing. See:

https://lore.kernel.org/lkml/20230403181342.210896-1-mathieu.desnoyers@efficios.com/

Thanks,

Mathieu

>
> node0_0.profile: 0.07% 0.07% [kernel.vmlinux] [k] native_queued_spin_lock_slowpath
> node0_1.profile: 0.06% 0.06% [kernel.vmlinux] [k] native_queued_spin_lock_slowpath
> node0_2.profile: 0.09% 0.09% [kernel.vmlinux] [k] native_queued_spin_lock_slowpath
> node0_3.profile: 0.08% 0.08% [kernel.vmlinux] [k] native_queued_spin_lock_slowpath
> node0_4.profile: 0.09% 0.09% [kernel.vmlinux] [k] native_queued_spin_lock_slowpath
> node0_5.profile: 0.10% 0.10% [kernel.vmlinux] [k] native_queued_spin_lock_slowpath
> node0_6.profile: 0.10% 0.10% [kernel.vmlinux] [k] native_queued_spin_lock_slowpath
> node0_7.profile: 0.07% 0.07% [kernel.vmlinux] [k] native_queued_spin_lock_slowpath
> node0_8.profile: 0.08% 0.08% [kernel.vmlinux] [k] native_queued_spin_lock_slowpath
> node0_9.profile: 0.06% 0.06% [kernel.vmlinux] [k] native_queued_spin_lock_slowpath
> node1_0.profile: 0.41% 0.41% [kernel.vmlinux] [k] native_queued_spin_lock_slowpath
> node1_1.profile: 0.38% 0.38% [kernel.vmlinux] [k] native_queued_spin_lock_slowpath
> node1_2.profile: 0.44% 0.44% [kernel.vmlinux] [k] native_queued_spin_lock_slowpath
> node1_3.profile: 5.64% 5.64% [kernel.vmlinux] [k] native_queued_spin_lock_slowpath
> node1_4.profile: 6.08% 6.08% [kernel.vmlinux] [k] native_queued_spin_lock_slowpath
> node1_5.profile: 3.45% 3.45% [kernel.vmlinux] [k] native_queued_spin_lock_slowpath
> node1_6.profile: 2.09% 2.09% [kernel.vmlinux] [k] native_queued_spin_lock_slowpath
> node1_7.profile: 2.72% 2.72% [kernel.vmlinux] [k] native_queued_spin_lock_slowpath
> node1_8.profile: 0.16% 0.16% [kernel.vmlinux] [k] native_queued_spin_lock_slowpath
> node1_9.profile: 0.15% 0.15% [kernel.vmlinux] [k] native_queued_spin_lock_slowpath
> (those few profiles from node1's cpus that have more than 2% contention
> are from thermal functions)
>
> Tested-by: Aaron Lu <aaron.lu@intel.com> # lock contention part




--
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com

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