diff options
author | 2023-06-14 21:07:14 -0700 | |
---|---|---|
committer | 2023-06-20 17:03:43 -0700 | |
commit | 0650b2b2e62edfa9510ba0c80f42d98c4a748b12 (patch) | |
tree | 79c0f0cef4c45b7eb339a9fb18a4b5fd8a450979 /tools/perf/util/sharded_mutex.h | |
parent | tools: Fix incorrect calculation of object size by sizeof (diff) | |
download | linux-0650b2b2e62edfa9510ba0c80f42d98c4a748b12.tar.gz linux-0650b2b2e62edfa9510ba0c80f42d98c4a748b12.tar.bz2 linux-0650b2b2e62edfa9510ba0c80f42d98c4a748b12.zip |
perf sharded_mutex: Introduce sharded_mutex
Per object mutexes may come with significant memory cost while a
global mutex can suffer from unnecessary contention. A sharded mutex
is a compromise where objects are hashed and then a particular mutex
for the hash of the object used. Contention can be controlled by the
number of shards.
v2. Use hashmap.h's hash_bits in case of contention from alignment of
objects.
Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Andres Freund <andres@anarazel.de>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Yuan Can <yuancan@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Link: https://lore.kernel.org/r/20230615040715.2064350-1-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Diffstat (limited to 'tools/perf/util/sharded_mutex.h')
-rw-r--r-- | tools/perf/util/sharded_mutex.h | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/tools/perf/util/sharded_mutex.h b/tools/perf/util/sharded_mutex.h new file mode 100644 index 000000000000..7325e969eee3 --- /dev/null +++ b/tools/perf/util/sharded_mutex.h @@ -0,0 +1,29 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef PERF_SHARDED_MUTEX_H +#define PERF_SHARDED_MUTEX_H + +#include "mutex.h" +#include "hashmap.h" + +/* + * In a situation where a lock is needed per object, having a mutex can be + * relatively memory expensive (40 bytes on x86-64). If the object can be + * constantly hashed, a sharded mutex is an alternative global pool of mutexes + * where the mutex is looked up from a hash value. This can lead to collisions + * if the number of shards isn't large enough. + */ +struct sharded_mutex { + /* mutexes array is 1<<cap_bits in size. */ + unsigned int cap_bits; + struct mutex mutexes[]; +}; + +struct sharded_mutex *sharded_mutex__new(size_t num_shards); +void sharded_mutex__delete(struct sharded_mutex *sm); + +static inline struct mutex *sharded_mutex__get_mutex(struct sharded_mutex *sm, size_t hash) +{ + return &sm->mutexes[hash_bits(hash, sm->cap_bits)]; +} + +#endif /* PERF_SHARDED_MUTEX_H */ |