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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>
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This patch introduces RPC based communication between the changelog
translator and libgfchangelog. It replaces the old pathetic stream
based interaction that existed earlier (due to time constraints :-/).
Changelog, upon initialization starts a RPC server (rpcsvc) allowing
clients to invoke a probe API as a bootup mechanism to request for
event notifications. During probe, clients can choose an event
filter specifying the type(s) of events they are interested in. As
of now there is no way to change the event notification set once
the probe RPC call is made, but that is easier to implement.
The actual event notifications is done on a separate RPC session.
The client (libgfchangelog) itself starts and RPC server which the
changelog translator "connects back" during probe. Notifications
are dispatched by a bunch of threads from the server (translator)
and the client optionally orders them if ordered notifications
are requried. FOPs fill in their respective event details in a
buffer (rot-buffs to be particular) and a bunch of threads
(consumers) swap the buffers out of roatation and dispatch them
via RPC. To avoid writer starvation, then number of dispatcher
threads is one less than the number of buffer list in rot-buffs.x
libgfchangelog becomes purely callback based -- upon event
notification from the server (and re-ordering them if required)
invoke a callback routine specified by consumer(s).
A major part of the patch is also aimed at providing backward
compatibility for geo-replication, which was one of the main
consumer of the stream based API. Also, this patch does not\
"turn on" event notifications for all fops, just a bunch which
is currently in requirement. Another pain point is that the
server does not filter events before dispatching it to the
clients. That load is taken up by the client itself (although
it's done at the library layer rather than making it hard on
the callback implementor). This needs improvement and care
needs to be taken to not load the server up with expensive
filtering mechanisms.
Change-Id: Ibf60a432b68f2dfa60c6f9add2bcfd37a9c41395
BUG: 1170075
Signed-off-by: Venky Shankar <vshankar@redhat.com>
Reviewed-on: http://review.gluster.org/9708
Reviewed-by: Jeff Darcy <jdarcy@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>
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