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

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Message-Id: <20220412164059.42654-1-atrajeev@linux.vnet.ibm.com>
Date:   Tue, 12 Apr 2022 22:10:57 +0530
From:   Athira Rajeev <atrajeev@...ux.vnet.ibm.com>
To:     acme@...nel.org, jolsa@...nel.org, disgoel@...ux.vnet.ibm.com
Cc:     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: [PATCH V3 0/2] Fix perf bench numa to work with machines having #CPUs > 1K

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.

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