Re: [PATCH v2 3/4] perf record: apply affinity masks when reading mmap buffers

Alexey Budankov
2019-01-09T09:14:50Z

Hi,

On 02.01.2019 0:39, Jiri Olsa wrote:
> On Mon, Dec 24, 2018 at 03:27:17PM +0300, Alexey Budankov wrote:
>>
>> Build node cpu masks for mmap data buffers. Apply node cpu
>> masks to tool thread every time it references data buffers
>> cross node or cross cpu.
>>
>> Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
>> ---
>> Changes in v2:
>> - separated AIO buffers binding to patch 2/4
>> ---
>> tools/perf/builtin-record.c | 9 +++++++++
>> tools/perf/util/evlist.c | 6 +++++-
>> tools/perf/util/mmap.c | 12 ++++++++++++
>> tools/perf/util/mmap.h | 1 +
>> 4 files changed, 27 insertions(+), 1 deletion(-)
>>
>> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
>> index b26febb54d01..eea96794ee45 100644
>> --- a/tools/perf/builtin-record.c
>> +++ b/tools/perf/builtin-record.c
>> @@ -536,6 +536,9 @@ static int record__mmap_evlist(struct record *rec,
>> struct record_opts *opts = &rec->opts;
>> char msg[512];
>>
>> + if (opts->affinity != PERF_AFFINITY_SYS)
>> + cpu__setup_cpunode_map();
>> +
>> if (perf_evlist__mmap_ex(evlist, opts->mmap_pages,
>> opts->auxtrace_mmap_pages,
>> opts->auxtrace_snapshot_mode,
>> @@ -755,6 +758,12 @@ static int record__mmap_read_evlist(struct record *rec, struct perf_evlist *evli
>> struct perf_mmap *map = &maps[i];
>>
>> if (map->base) {
>> + if (rec->opts.affinity != PERF_AFFINITY_SYS &&
>> + !CPU_EQUAL(&rec->affinity_mask, &map->affinity_mask)) {
>> + CPU_ZERO(&rec->affinity_mask);
>> + CPU_OR(&rec->affinity_mask, &rec->affinity_mask, &map->affinity_mask);
>> + sched_setaffinity(0, sizeof(rec->affinity_mask), &rec->affinity_mask);
>
> all this code depends on aio and LIBNUMA, let's keep it there then

Please note that thread migration improves performance for serial case too:

BENCH REPORT BASED ELAPSED TIME BASED
v4.20.0-rc5
(tip perf/core):

(current) SERIAL-SYS / BASE : 1.27x (14.37/11.31), 1.29x (15.19/11.69)
SERIAL-NODE / BASE : 1.15x (13.04/11.31), 1.17x (13.79/11.69)
SERIAL-CPU / BASE : 1.00x (11.32/11.31), 1.01x (11.89/11.69)

mbind() for AIO buffers is the only related adjustment.

>
> also please add this and the affinity_mask setup code below to a function

Separated the code into record__adjust_affinity() and perf_mmap__setup_affinity_mask() in v3.

Thanks,
Alexey

>
> thanks,
> jirka
>
>> + }
>> if (!record__aio_enabled(rec)) {
>> if (perf_mmap__push(map, rec, record__pushfn) != 0) {
>> rc = -1;
>> diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
>> index 60e825be944a..5ca5bb5ea0db 100644
>> --- a/tools/perf/util/evlist.c
>> +++ b/tools/perf/util/evlist.c
>> @@ -1028,7 +1028,11 @@ int perf_evlist__mmap_ex(struct perf_evlist *evlist, unsigned int pages,
>> * Its value is decided by evsel's write_backward.
>> * So &mp should not be passed through const pointer.
>> */
>> - struct mmap_params mp = { .nr_cblocks = nr_cblocks, .affinity = affinity };
>> + struct mmap_params mp = {
>> + .nr_cblocks = nr_cblocks,
>> + .affinity = affinity,
>> + .cpu_map = cpus
>> + };
>>
>> if (!evlist->mmap)
>> evlist->mmap = perf_evlist__alloc_mmap(evlist, false);
>> diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
>> index 742fa9a8e498..a2095e4eda4b 100644
>> --- a/tools/perf/util/mmap.c
>> +++ b/tools/perf/util/mmap.c
>> @@ -361,6 +361,7 @@ void perf_mmap__munmap(struct perf_mmap *map)
>>
>> int perf_mmap__mmap(struct perf_mmap *map, struct mmap_params *mp, int fd, int cpu)
>> {
>> + int c, nr_cpus, node;
>> /*
>> * The last one will be done at perf_mmap__consume(), so that we
>> * make sure we don't prevent tools from consuming every last event in
>> @@ -389,6 +390,17 @@ int perf_mmap__mmap(struct perf_mmap *map, struct mmap_params *mp, int fd, int c
>> map->cpu = cpu;
>>
>> CPU_ZERO(&map->affinity_mask);
>> + if (mp->affinity == PERF_AFFINITY_NODE && cpu__max_node() > 1) {
>> + nr_cpus = cpu_map__nr(mp->cpu_map);
>> + node = cpu__get_node(map->cpu);
>> + for (c = 0; c < nr_cpus; c++) {
>> + if (cpu__get_node(c) == node) {
>> + CPU_SET(c, &map->affinity_mask);
>> + }
>> + }
>> + } else if (mp->affinity == PERF_AFFINITY_CPU) {
>> + CPU_SET(map->cpu, &map->affinity_mask);
>> + }
>>
>> if (auxtrace_mmap__mmap(&map->auxtrace_mmap,
>> &mp->auxtrace_mp, map->base, fd))
>> diff --git a/tools/perf/util/mmap.h b/tools/perf/util/mmap.h
>> index e566c19b242b..b3f724fad22e 100644
>> --- a/tools/perf/util/mmap.h
>> +++ b/tools/perf/util/mmap.h
>> @@ -72,6 +72,7 @@ enum bkw_mmap_state {
>> struct mmap_params {
>> int prot, mask, nr_cblocks, affinity;
>> struct auxtrace_mmap_params auxtrace_mp;
>> + const struct cpu_map *cpu_map;
>> };
>>
>> int perf_mmap__mmap(struct perf_mmap *map, struct mmap_params *mp, int fd, int cpu);
>