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Subject[PATCH v4 3/3] perf record: adapt affinity to machines with #CPUs > 1K
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Date

Use struct mmap_cpu_mask type for tool's thread and mmap data
buffers to overcome current 1024 CPUs mask size limitation of
cpu_set_t type.

Currently glibc cpu_set_t type has internal mask size limit
of 1024 CPUs. Moving to struct mmap_cpu_mask type allows
overcoming that limit. tools bitmap API is used to manipulate
objects of struct mmap_cpu_mask type.

Reported-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
---
tools/perf/builtin-record.c | 28 ++++++++++++++++++++++------
tools/perf/util/mmap.c | 27 +++++++++++++++++++++------
tools/perf/util/mmap.h | 2 +-
3 files changed, 44 insertions(+), 13 deletions(-)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index fb19ef63cc35..7bc83755ef8c 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -62,6 +62,7 @@
#include <linux/string.h>
#include <linux/time64.h>
#include <linux/zalloc.h>
+#include <linux/bitmap.h>

struct switch_output {
bool enabled;
@@ -93,7 +94,7 @@ struct record {
bool timestamp_boundary;
struct switch_output switch_output;
unsigned long long samples;
- cpu_set_t affinity_mask;
+ struct mmap_cpu_mask affinity_mask;
unsigned long output_max_size; /* = 0: unlimited */
};

@@ -961,10 +962,15 @@ static struct perf_event_header finished_round_event = {
static void record__adjust_affinity(struct record *rec, struct mmap *map)
{
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);
+ !bitmap_equal(rec->affinity_mask.bits, map->affinity_mask.bits,
+ rec->affinity_mask.nbits)) {
+ bitmap_zero(rec->affinity_mask.bits, rec->affinity_mask.nbits);
+ bitmap_or(rec->affinity_mask.bits, rec->affinity_mask.bits,
+ map->affinity_mask.bits, rec->affinity_mask.nbits);
+ sched_setaffinity(0, MMAP_CPU_MASK_BYTES(&rec->affinity_mask),
+ (cpu_set_t *)rec->affinity_mask.bits);
+ if (verbose == 2)
+ mmap_cpu_mask__scnprintf(&rec->affinity_mask, "thread");
}
}

@@ -2433,7 +2439,6 @@ int cmd_record(int argc, const char **argv)
# undef REASON
#endif

- CPU_ZERO(&rec->affinity_mask);
rec->opts.affinity = PERF_AFFINITY_SYS;

rec->evlist = evlist__new();
@@ -2499,6 +2504,16 @@ int cmd_record(int argc, const char **argv)

symbol__init(NULL);

+ if (rec->opts.affinity != PERF_AFFINITY_SYS) {
+ rec->affinity_mask.nbits = cpu__max_cpu();
+ rec->affinity_mask.bits = bitmap_alloc(rec->affinity_mask.nbits);
+ if (!rec->affinity_mask.bits) {
+ pr_err("Failed to allocate thread mask for %ld cpus\n", rec->affinity_mask.nbits);
+ return -ENOMEM;
+ }
+ pr_debug2("thread mask[%ld]: empty\n", rec->affinity_mask.nbits);
+ }
+
err = record__auxtrace_init(rec);
if (err)
goto out;
@@ -2613,6 +2628,7 @@ int cmd_record(int argc, const char **argv)

err = __cmd_record(&record, argc, argv);
out:
+ bitmap_free(rec->affinity_mask.bits);
evlist__delete(rec->evlist);
symbol__exit();
auxtrace_record__free(rec->itr);
diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
index 43c12b4a3e17..7f573f646431 100644
--- a/tools/perf/util/mmap.c
+++ b/tools/perf/util/mmap.c
@@ -219,6 +219,8 @@ static void perf_mmap__aio_munmap(struct mmap *map __maybe_unused)

void mmap__munmap(struct mmap *map)
{
+ bitmap_free(map->affinity_mask.bits);
+
perf_mmap__aio_munmap(map);
if (map->data != NULL) {
munmap(map->data, mmap__mmap_len(map));
@@ -227,7 +229,7 @@ void mmap__munmap(struct mmap *map)
auxtrace_mmap__munmap(&map->auxtrace_mmap);
}

-static void build_node_mask(int node, cpu_set_t *mask)
+static void build_node_mask(int node, struct mmap_cpu_mask *mask)
{
int c, cpu, nr_cpus;
const struct perf_cpu_map *cpu_map = NULL;
@@ -240,17 +242,23 @@ static void build_node_mask(int node, cpu_set_t *mask)
for (c = 0; c < nr_cpus; c++) {
cpu = cpu_map->map[c]; /* map c index to online cpu index */
if (cpu__get_node(cpu) == node)
- CPU_SET(cpu, mask);
+ set_bit(cpu, mask->bits);
}
}

-static void perf_mmap__setup_affinity_mask(struct mmap *map, struct mmap_params *mp)
+static int perf_mmap__setup_affinity_mask(struct mmap *map, struct mmap_params *mp)
{
- CPU_ZERO(&map->affinity_mask);
+ map->affinity_mask.nbits = cpu__max_cpu();
+ map->affinity_mask.bits = bitmap_alloc(map->affinity_mask.nbits);
+ if (!map->affinity_mask.bits)
+ return -1;
+
if (mp->affinity == PERF_AFFINITY_NODE && cpu__max_node() > 1)
build_node_mask(cpu__get_node(map->core.cpu), &map->affinity_mask);
else if (mp->affinity == PERF_AFFINITY_CPU)
- CPU_SET(map->core.cpu, &map->affinity_mask);
+ set_bit(map->core.cpu, map->affinity_mask.bits);
+
+ return 0;
}

int mmap__mmap(struct mmap *map, struct mmap_params *mp, int fd, int cpu)
@@ -261,7 +269,14 @@ int mmap__mmap(struct mmap *map, struct mmap_params *mp, int fd, int cpu)
return -1;
}

- perf_mmap__setup_affinity_mask(map, mp);
+ if (perf_mmap__setup_affinity_mask(map, mp)) {
+ pr_debug2("failed to alloc mmap affinity mask, error %d\n",
+ errno);
+ return -1;
+ }
+
+ if (verbose == 2)
+ mmap_cpu_mask__scnprintf(&map->affinity_mask, "mmap");

map->core.flush = mp->flush;

diff --git a/tools/perf/util/mmap.h b/tools/perf/util/mmap.h
index ef51667fabcb..9d5f589f02ae 100644
--- a/tools/perf/util/mmap.h
+++ b/tools/perf/util/mmap.h
@@ -40,7 +40,7 @@ struct mmap {
int nr_cblocks;
} aio;
#endif
- cpu_set_t affinity_mask;
+ struct mmap_cpu_mask affinity_mask;
void *data;
int comp_level;
};
--
2.20.1
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