linux-kernel - Re: [PATCH V3 0/2] Fix perf bench numa to work with machines having #CPUs

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Message-ID: <YlgQj40R3so8xz50@kernel.org>
Date:   Thu, 14 Apr 2022 09:16:15 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Athira Rajeev <atrajeev@...ux.vnet.ibm.com>
Cc:     jolsa@...nel.org, disgoel@...ux.vnet.ibm.com, mpe@...erman.id.au,
        linux-perf-users@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        maddy@...ux.vnet.ibm.com, rnsastry@...ux.ibm.com,
        kjain@...ux.ibm.com, linux-kernel@...r.kernel.org,
        srikar@...ux.vnet.ibm.com, irogers@...gle.com
Subject: Re: [PATCH V3 0/2] Fix perf bench numa to work with machines having
 #CPUs > 1K

Em Tue, Apr 12, 2022 at 10:10:57PM +0530, Athira Rajeev escreveu:
> The perf benchmark for collections: numa hits failure in system
> configuration with CPU's more than 1024. These benchmarks uses
> "sched_getaffinity" and "sched_setaffinity" in the code to
> work with affinity.

Thanks, applied.

- Arnaldo

 
> Example snippet from numa benchmark:
> <<>>
> perf: bench/numa.c:302: bind_to_node: Assertion `!(ret)' failed.
> Aborted (core dumped)
> <<>>
> 
> bind_to_node function uses "sched_getaffinity" to save the cpumask.
> This fails with EINVAL because the default mask size in glibc is 1024
> 
> To overcome this 1024 CPUs mask size limitation of cpu_set_t,
> change the mask size using the CPU_*_S macros ie, use CPU_ALLOC to
> allocate cpumask, CPU_ALLOC_SIZE for size, CPU_SET_S to set mask bit.
> 
> Fix all the relevant places in the code to use mask size which is large
> enough to represent number of possible CPU's in the system.
> 
> This patchset also address a fix for parse_setup_cpu_list function in
> numa bench to check if input CPU is online before binding task to
> that CPU. This is to fix failures where, though CPU number is within
> max CPU, it could happen that CPU is offline. Here, sched_setaffinity
> will result in failure when using cpumask having that cpu bit set
> in the mask.
> 
> Patch 1 address fix for parse_setup_cpu_list to check if CPU used to bind
> task is online. Patch 2 has fix for bench numa to work with machines
> having #CPUs > 1K
> 
> Athira Rajeev (2):
>   tools/perf: Fix perf bench numa testcase to check if CPU used to bind
>     task is online
>   perf bench: Fix numa bench to fix usage of affinity for machines with
>     #CPUs > 1K
> 
> Changelog:
> v2 -> v3
> Link to the v2 version :
> https://lore.kernel.org/all/20220406175113.87881-1-atrajeev@linux.vnet.ibm.com/
>  - From the v2 version, patch 1 and patch 2 are now part of upstream.
>  - This v3 version separates patch 3 and patch 4 to address review
>    comments from arnaldo which includes using sysfs__read_str for reading
>    sysfs file and fixing the compilation issues observed in debian
> 
>  tools/perf/bench/numa.c  | 136 +++++++++++++++++++++++++++++----------
>  tools/perf/util/header.c |  51 +++++++++++++++
>  tools/perf/util/header.h |   1 +
>  3 files changed, 153 insertions(+), 35 deletions(-)
> 
> -- 
> 2.35.1

-- 

- Arnaldo