[PATCH v2 0/4] Fix perf bench numa, futex and epoll to work with machines having #CPUs > 1K

Athira Rajeev
2022-04-06T19:44:50Z

The perf benchmark for collections: numa, futex and epoll
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.

Similarly in futex and epoll benchmark, uses sched_setaffinity during
pthread_create with affinity. And since it returns EINVAL in such system
configuration, benchmark doesn't run.

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.

Fix 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 and Patch 2 address fix for perf bench futex and perf bench
epoll benchmark. Patch 3 and Patch 4 address fix in perf bench numa
benchmark

Athira Rajeev (4):
tools/perf: Fix perf bench futex to correct usage of affinity for
machines with #CPUs > 1K
tools/perf: Fix perf bench epoll to correct usage of affinity for
machines with #CPUs > 1K
tools/perf: Fix perf numa bench to fix usage of affinity for machines
with #CPUs > 1K
tools/perf: Fix perf bench numa testcase to check if CPU used to bind
task is online

Changelog:
From v1 -> v2:
Addressed review comment from Ian Rogers to do
CPU_FREE in a cleaner way.
Added Tested-by from Disha Goel

tools/perf/bench/epoll-ctl.c | 25 ++++--
tools/perf/bench/epoll-wait.c | 25 ++++--
tools/perf/bench/futex-hash.c | 26 ++++--
tools/perf/bench/futex-lock-pi.c | 21 +++--
tools/perf/bench/futex-requeue.c | 21 +++--
tools/perf/bench/futex-wake-parallel.c | 21 +++--
tools/perf/bench/futex-wake.c | 22 ++++--
tools/perf/bench/numa.c | 105 ++++++++++++++++++-------
tools/perf/util/header.c | 43 ++++++++++
tools/perf/util/header.h | 1 +
10 files changed, 242 insertions(+), 68 deletions(-)

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2.35.1