On Thu, 18 Feb 2021, Peter Xu wrote:
> parse_cpumask() is too strict for oslat, in that use_current_cpuset() will
> filter out all the cores that are not allowed for current process to run. This
> seems to be unnecessary at least for oslat. For example, the bash process that
> runs the oslat program may have a sched affinity of 0-2, however it's still
> legal to have it start a oslat thread running on the cores outside 0-2 as long
> as the follow up sched_setaffinity() will succeed.
>
> numa_parse_cpustring_all() suites exactly for this case, which should already
> have considered sysconf(_SC_NPROCESSORS_ONLN) limit. Use that instead.
>
> Since at it, also remove initialization of cpu_set variable otherwise it's
> leaked in previous parse_cpumask too: numa_parse_cpustring_all() will return a
> newly allocated buffer already. Quotting from manual:
>
> numa_parse_nodestring() parses a character string list of nodes into a bit
> mask. The bit mask is allocated by numa_allocate_nodemask().
>
> numa_parse_nodestring_all() is similar to numa_parse_nodestring, but can
> parse all possible nodes, not only current nodeset.
>
> Cc: John Kacur <jkacur@xxxxxxxxxx>
> Cc: Daniel Wagner <dwagner@xxxxxxx>
> Cc: Clark Williams <williams@xxxxxxxxxx>
> Reported-by: Pradipta Kumar Sahoo <psahoo@xxxxxxxxxx>
> Reported-by: Mike Stowell <mstowell@xxxxxxxxxx>
> Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
> ---
> src/oslat/oslat.c | 8 ++------
> 1 file changed, 2 insertions(+), 6 deletions(-)
>
> diff --git a/src/oslat/oslat.c b/src/oslat/oslat.c
> index b2c5373..465a694 100644
> --- a/src/oslat/oslat.c
> +++ b/src/oslat/oslat.c
> @@ -785,7 +785,6 @@ int main(int argc, char *argv[])
> struct thread *threads;
> int i, n_cores;
> struct bitmask *cpu_set = NULL;
> - int max_cpus = sysconf(_SC_NPROCESSORS_ONLN);
>
> #ifdef FRC_MISSING
> printf("This architecture is not yet supported. "
> @@ -797,10 +796,6 @@ int main(int argc, char *argv[])
> exit(1);
> }
>
> - cpu_set = numa_allocate_cpumask();
> - if (!cpu_set)
> - fatal("oslat: Could not allocate cpumask\n");
> -
> g.app_name = argv[0];
> g.rtprio = 0;
> g.bucket_size = BUCKET_SIZE;
> @@ -817,7 +812,8 @@ int main(int argc, char *argv[])
> if (!g.cpu_list)
> g.cpu_list = strdup("all");
>
> - if (parse_cpumask(g.cpu_list, max_cpus, &cpu_set) != 0)
> + cpu_set = numa_parse_cpustring_all(g.cpu_list);
> + if (!cpu_set)
> fatal("oslat: parse_cpumask failed.\n");
> n_cores = numa_bitmask_weight(cpu_set);
>
> --
> 2.26.2
>
>
Signed-off-by: John Kacur <jkacur@xxxxxxxxxx>
