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authorMohit Agrawal <moagrawa@redhat.com>2017-10-20 12:39:29 +0530
committerAmar Tumballi <amarts@redhat.com>2017-12-12 09:05:56 +0000
commit430484c92ab5a6234958d1143e0bb14aeb0cd1c0 (patch)
tree0fb39e2a1c9be94396736d76b9aaababf232821b /xlators/debug/io-stats
parent8483ed87165c1695b513e223549d33d2d63891d9 (diff)
glusterfs: Use gcc builtin ATOMIC operator to increase/decreate refcount.
Problem: In glusterfs code base we call mutex_lock/unlock to take reference/dereference for a object.Sometime it could be reason for lock contention also. Solution: There is no need to use mutex to increase/decrease ref counter, instead of using mutex use gcc builtin ATOMIC operation. Test: I have not observed yet how much performance gain after apply this patch specific to glusterfs but i have tested same with below small program(mutex and atomic both) and get good difference. static int numOuterLoops; static void * threadFunc(void *arg) { int j; for (j = 0; j < numOuterLoops; j++) { __atomic_add_fetch (&glob, 1,__ATOMIC_ACQ_REL); } return NULL; } int main(int argc, char *argv[]) { int opt, s, j; int numThreads; pthread_t *thread; int verbose; int64_t n = 0; if (argc < 2 ) { printf(" Please provide 2 args Num of threads && Outer Loop\n"); exit (-1); } numThreads = atoi(argv[1]); numOuterLoops = atoi (argv[2]); if (1) { printf("\tthreads: %d; outer loops: %d;\n", numThreads, numOuterLoops); } thread = calloc(numThreads, sizeof(pthread_t)); if (thread == NULL) { printf ("calloc error so exit\n"); exit (-1); } __atomic_store (&glob, &n, __ATOMIC_RELEASE); for (j = 0; j < numThreads; j++) { s = pthread_create(&thread[j], NULL, threadFunc, NULL); if (s != 0) { printf ("pthread_create failed so exit\n"); exit (-1); } } for (j = 0; j < numThreads; j++) { s = pthread_join(thread[j], NULL); if (s != 0) { printf ("pthread_join failed so exit\n"); exit (-1); } } printf("glob value is %ld\n",__atomic_load_n (&glob,__ATOMIC_RELAXED)); exit(0); } time ./thr_count 800 800000 threads: 800; outer loops: 800000; glob value is 640000000 real 1m10.288s user 0m57.269s sys 3m31.565s time ./thr_count_atomic 800 800000 threads: 800; outer loops: 800000; glob value is 640000000 real 0m20.313s user 1m20.558s sys 0m0.028 Change-Id: Ie5030a52ea264875e002e108dd4b207b15ab7cc7 Signed-off-by: Mohit Agrawal <moagrawa@redhat.com>
Diffstat (limited to 'xlators/debug/io-stats')
-rw-r--r--xlators/debug/io-stats/src/io-stats.c29
1 files changed, 12 insertions, 17 deletions
diff --git a/xlators/debug/io-stats/src/io-stats.c b/xlators/debug/io-stats/src/io-stats.c
index c0cd0e2..4864c67 100644
--- a/xlators/debug/io-stats/src/io-stats.c
+++ b/xlators/debug/io-stats/src/io-stats.c
@@ -74,7 +74,7 @@ struct ios_stat {
char *filename;
gf_atomic_t counters[IOS_STATS_TYPE_MAX];
struct ios_stat_lat thru_counters [IOS_STATS_THRU_MAX];
- int refcnt;
+ gf_atomic_t refcnt;
};
struct ios_stat_list {
@@ -333,13 +333,10 @@ ios_fd_ctx_set (fd_t *fd, xlator_t *this, struct ios_fd *iosfd)
static int
ios_stat_ref (struct ios_stat *iosstat)
{
- LOCK (&iosstat->lock);
- {
- iosstat->refcnt++;
- }
- UNLOCK (&iosstat->lock);
+ uint64_t refcnt = 0;
+ refcnt = GF_ATOMIC_INC (iosstat->refcnt);
- return iosstat->refcnt;
+ return refcnt;
}
@@ -347,18 +344,16 @@ static int
ios_stat_unref (struct ios_stat *iosstat)
{
int cleanup = 0;
- LOCK (&iosstat->lock);
- {
- iosstat->refcnt--;
- if (iosstat->refcnt == 0) {
- if (iosstat->filename) {
- GF_FREE (iosstat->filename);
- iosstat->filename = NULL;
- }
- cleanup = 1;
+ uint64_t refcnt = 0;
+
+ refcnt = GF_ATOMIC_DEC (iosstat->refcnt);
+ if (refcnt == 0) {
+ if (iosstat->filename) {
+ GF_FREE (iosstat->filename);
+ iosstat->filename = NULL;
}
+ cleanup = 1;
}
- UNLOCK (&iosstat->lock);
if (cleanup) {
LOCK_DESTROY (&iosstat->lock);