Re: [PATCH v2 3/4] tools/perf: Fix perf numa bench to fix usage of affinity for machines with #CPUs > 1K

Srikar Dronamraju
2022-04-08T12:29:04Z

* Athira Rajeev <atrajeev@linux.vnet.ibm.com> [2022-04-06 23:21:12]:

> perf bench numa testcase fails on systems with CPU's
> more than 1K.
>
> Testcase: perf bench numa mem -p 1 -t 3 -P 512 -s 100 -zZ0qcm --thp 1
> Snippet of code:
> <<>>
> perf: bench/numa.c:302: bind_to_node: Assertion `!(ret)' failed.
> Aborted (core dumped)
> <<>>
>
> bind_to_node function uses "sched_getaffinity" to save the original
> cpumask and this call is returning EINVAL ((invalid argument).
> This happens 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. Apart from fixing this
> for "orig_mask", apply same logic to "mask" as well which is used to
> setaffinity so that mask size is large enough to represent number
> of possible CPU's in the system.
>
> sched_getaffinity is used in one more place in perf numa bench. It
> is in "bind_to_cpu" function. Apply the same logic there also. Though
> currently no failure is reported from there, it is ideal to change
> getaffinity to work with such system configurations having CPU's more
> than default mask size supported by glibc.
>
> Also fix "sched_setaffinity" to use mask size which is large enough
> to represent number of possible CPU's in the system.
>
> Fixed all places where "bind_cpumask" which is part of "struct
> thread_data" is used such that bind_cpumask works in all configuration.
>
> Tested-by: Disha Goel <disgoel@linux.vnet.ibm.com>
> Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
> Reported-by: Disha Goel <disgoel@linux.vnet.ibm.com>

Looks good to me.

Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

> ---
> tools/perf/bench/numa.c | 97 ++++++++++++++++++++++++++++++-----------
> 1 file changed, 71 insertions(+), 26 deletions(-)
>
> diff --git a/tools/perf/bench/numa.c b/tools/perf/bench/numa.c
> index f2640179ada9..29e41e32bd88 100644
> --- a/tools/perf/bench/numa.c
> +++ b/tools/perf/bench/numa.c
> @@ -54,7 +54,7 @@
>
> struct thread_data {
> int curr_cpu;
> - cpu_set_t bind_cpumask;
> + cpu_set_t *bind_cpumask;
> int bind_node;
> u8 *process_data;
> int process_nr;
> @@ -266,46 +266,71 @@ static bool node_has_cpus(int node)
> return ret;
> }
>
> -static cpu_set_t bind_to_cpu(int target_cpu)
> +static cpu_set_t *bind_to_cpu(int target_cpu)
> {
> - cpu_set_t orig_mask, mask;
> + int nrcpus = numa_num_possible_cpus();
> + cpu_set_t *orig_mask, *mask;
> + size_t size;
> int ret;
>
> - ret = sched_getaffinity(0, sizeof(orig_mask), &orig_mask);
> - BUG_ON(ret);
> + orig_mask = CPU_ALLOC(nrcpus);
> + BUG_ON(!orig_mask);
> + size = CPU_ALLOC_SIZE(nrcpus);
> + CPU_ZERO_S(size, orig_mask);
> +
> + ret = sched_getaffinity(0, size, orig_mask);
> + if (ret) {
> + CPU_FREE(orig_mask);
> + BUG_ON(ret);
> + }
>
> - CPU_ZERO(&mask);
> + mask = CPU_ALLOC(nrcpus);
> + BUG_ON(!mask);
> + CPU_ZERO_S(size, mask);
>
> if (target_cpu == -1) {
> int cpu;
>
> for (cpu = 0; cpu < g->p.nr_cpus; cpu++)
> - CPU_SET(cpu, &mask);
> + CPU_SET_S(cpu, size, mask);
> } else {
> BUG_ON(target_cpu < 0 || target_cpu >= g->p.nr_cpus);
> - CPU_SET(target_cpu, &mask);
> + CPU_SET_S(target_cpu, size, mask);
> }
>
> - ret = sched_setaffinity(0, sizeof(mask), &mask);
> + ret = sched_setaffinity(0, size, mask);
> + CPU_FREE(mask);
> BUG_ON(ret);
>
> return orig_mask;
> }
>
> -static cpu_set_t bind_to_node(int target_node)
> +static cpu_set_t *bind_to_node(int target_node)
> {
> - cpu_set_t orig_mask, mask;
> + int nrcpus = numa_num_possible_cpus();
> + cpu_set_t *orig_mask, *mask;
> + size_t size;
> int cpu;
> int ret;
>
> - ret = sched_getaffinity(0, sizeof(orig_mask), &orig_mask);
> - BUG_ON(ret);
> + orig_mask = CPU_ALLOC(nrcpus);
> + BUG_ON(!orig_mask);
> + size = CPU_ALLOC_SIZE(nrcpus);
> + CPU_ZERO_S(size, orig_mask);
> +
> + ret = sched_getaffinity(0, size, orig_mask);
> + if (ret) {
> + CPU_FREE(orig_mask);
> + BUG_ON(ret);
> + }
>
> - CPU_ZERO(&mask);
> + mask = CPU_ALLOC(nrcpus);
> + BUG_ON(!mask);
> + CPU_ZERO_S(size, mask);
>
> if (target_node == NUMA_NO_NODE) {
> for (cpu = 0; cpu < g->p.nr_cpus; cpu++)
> - CPU_SET(cpu, &mask);
> + CPU_SET_S(cpu, size, mask);
> } else {
> struct bitmask *cpumask = numa_allocate_cpumask();
>
> @@ -313,24 +338,29 @@ static cpu_set_t bind_to_node(int target_node)
> if (!numa_node_to_cpus(target_node, cpumask)) {
> for (cpu = 0; cpu < (int)cpumask->size; cpu++) {
> if (numa_bitmask_isbitset(cpumask, cpu))
> - CPU_SET(cpu, &mask);
> + CPU_SET_S(cpu, size, mask);
> }
> }
> numa_free_cpumask(cpumask);
> }
>
> - ret = sched_setaffinity(0, sizeof(mask), &mask);
> + ret = sched_setaffinity(0, size, mask);
> + CPU_FREE(mask);
> BUG_ON(ret);
>
> return orig_mask;
> }
>
> -static void bind_to_cpumask(cpu_set_t mask)
> +static void bind_to_cpumask(cpu_set_t *mask)
> {
> int ret;
> + size_t size = CPU_ALLOC_SIZE(numa_num_possible_cpus());
>
> - ret = sched_setaffinity(0, sizeof(mask), &mask);
> - BUG_ON(ret);
> + ret = sched_setaffinity(0, size, mask);
> + if (ret) {
> + CPU_FREE(mask);
> + BUG_ON(ret);
> + }
> }
>
> static void mempol_restore(void)
> @@ -376,7 +406,7 @@ do { \
> static u8 *alloc_data(ssize_t bytes0, int map_flags,
> int init_zero, int init_cpu0, int thp, int init_random)
> {
> - cpu_set_t orig_mask;
> + cpu_set_t *orig_mask;
> ssize_t bytes;
> u8 *buf;
> int ret;
> @@ -434,6 +464,7 @@ static u8 *alloc_data(ssize_t bytes0, int map_flags,
> /* Restore affinity: */
> if (init_cpu0) {
> bind_to_cpumask(orig_mask);
> + CPU_FREE(orig_mask);
> mempol_restore();
> }
>
> @@ -589,6 +620,7 @@ static int parse_setup_cpu_list(void)
> BUG_ON(bind_cpu_0 > bind_cpu_1);
>
> for (bind_cpu = bind_cpu_0; bind_cpu <= bind_cpu_1; bind_cpu += step) {
> + size_t size = CPU_ALLOC_SIZE(g->p.nr_cpus);
> int i;
>
> for (i = 0; i < mul; i++) {
> @@ -608,10 +640,12 @@ static int parse_setup_cpu_list(void)
> tprintf("%2d", bind_cpu);
> }
>
> - CPU_ZERO(&td->bind_cpumask);
> + td->bind_cpumask = CPU_ALLOC(g->p.nr_cpus);
> + BUG_ON(!td->bind_cpumask);
> + CPU_ZERO_S(size, td->bind_cpumask);
> for (cpu = bind_cpu; cpu < bind_cpu+bind_len; cpu++) {
> BUG_ON(cpu < 0 || cpu >= g->p.nr_cpus);
> - CPU_SET(cpu, &td->bind_cpumask);
> + CPU_SET_S(cpu, size, td->bind_cpumask);
> }
> t++;
> }
> @@ -1241,7 +1275,7 @@ static void *worker_thread(void *__tdata)
> * by migrating to CPU#0:
> */
> if (first_task && g->p.perturb_secs && (int)(stop.tv_sec - last_perturbance) >= g->p.perturb_secs) {
> - cpu_set_t orig_mask;
> + cpu_set_t *orig_mask;
> int target_cpu;
> int this_cpu;
>
> @@ -1265,6 +1299,7 @@ static void *worker_thread(void *__tdata)
> printf(" (injecting perturbalance, moved to CPU#%d)\n", target_cpu);
>
> bind_to_cpumask(orig_mask);
> + CPU_FREE(orig_mask);
> }
>
> if (details >= 3) {
> @@ -1398,21 +1433,31 @@ static void init_thread_data(void)
>
> for (t = 0; t < g->p.nr_tasks; t++) {
> struct thread_data *td = g->threads + t;
> + size_t cpuset_size = CPU_ALLOC_SIZE(g->p.nr_cpus);
> int cpu;
>
> /* Allow all nodes by default: */
> td->bind_node = NUMA_NO_NODE;
>
> /* Allow all CPUs by default: */
> - CPU_ZERO(&td->bind_cpumask);
> + td->bind_cpumask = CPU_ALLOC(g->p.nr_cpus);
> + BUG_ON(!td->bind_cpumask);
> + CPU_ZERO_S(cpuset_size, td->bind_cpumask);
> for (cpu = 0; cpu < g->p.nr_cpus; cpu++)
> - CPU_SET(cpu, &td->bind_cpumask);
> + CPU_SET_S(cpu, cpuset_size, td->bind_cpumask);
> }
> }
>
> static void deinit_thread_data(void)
> {
> ssize_t size = sizeof(*g->threads)*g->p.nr_tasks;
> + int t;
> +
> + /* Free the bind_cpumask allocated for thread_data */
> + for (t = 0; t < g->p.nr_tasks; t++) {
> + struct thread_data *td = g->threads + t;
> + CPU_FREE(td->bind_cpumask);
> + }
>
> free_data(g->threads, size);
> }
> --
> 2.35.1
>