linux-kernel - Re: [PATCH v3 0/6] lib: Extend bitmap find binary operations

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Message-ID: <f0dbd190-df68-4b0e-963c-d6f7ada5dc77@efficios.com>
Date: Mon, 2 Sep 2024 17:42:50 -0400
From: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To: Yury Norov <yury.norov@...il.com>
Cc: Rasmus Villemoes <linux@...musvillemoes.dk>,
 linux-kernel@...r.kernel.org, Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH v3 0/6] lib: Extend bitmap find binary operations

On 2024-08-30 19:02, Yury Norov wrote:
> On Fri, Aug 30, 2024 at 03:10:37PM -0400, Mathieu Desnoyers wrote:
>> Extend bitmap find.h and cpumask.h with additional binary operations
>> such as "nor".
>>
>> Also extend the testing and benchmark coverage of those bitmap find with
>> binary operations.
>>
>> This is useful for NUMA-aware rseq concurrency IDs which depend on this
>> series. The series can be found at:
>>
>> https://lore.kernel.org/lkml/20240823185946.418340-1-mathieu.desnoyers@efficios.com/
>>
> 
> Added in bitmap-for-next for testing.

Hi Yuri,

FYI, after a lot of performance results analysis on variations over
the NUMA-aware rseq patch, I figured I need to take a drastically
different (and much simpler) approach to solve this in order to improve
cache locality as well, and it turns out I likely won't need the new
bitwise ops added by this series.

So feel free to keep it as a general improvement, or to drop it for
now.

Thanks,

Mathieu

> 
> Thanks,
> Yury
> 
>>
>> Mathieu Desnoyers (6):
>>    lib: Clarify comment on top of find_next_andnot_bit
>>    lib: Implement find_{first,next,nth}_nor_bit, for_each_nor_bit,
>>      find_first_andnot_bit
>>    lib: test bitmap sets binary operation iterators
>>    lib: Fix test_find_first_and_bit and test_find_next_and_bit benchmark
>>    lib: benchmark bitmap sets binary operation find
>>    cpumask: Implement cpumask_{first,next}_{nor,andnot}
>>
>>   include/linux/cpumask.h  |  60 ++++++++++++++++
>>   include/linux/find.h     | 124 +++++++++++++++++++++++++++++++--
>>   lib/find_bit.c           |  36 ++++++++++
>>   lib/find_bit_benchmark.c | 143 +++++++++++++++++++++++++++++++++------
>>   lib/test_bitmap.c        |  81 ++++++++++++++++++++++
>>   5 files changed, 418 insertions(+), 26 deletions(-)
>>
>> -- 
>> 2.39.2

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