rpcsvc: provide each request handler thread its own queue

A single global per program queue is contended by all request handler
threads and event threads. This can lead to high contention. So,
reduce the contention by providing each request handler thread its own
private queue.

Thanks to "Manoj Pillai"<mpillai@redhat.com> for the idea of pairing a
single queue with a fixed request-handler-thread and event-thread,
which brought down the performance regression due to overhead of
queuing significantly.

Thanks to "Xavi Hernandez"<xhernandez@redhat.com> for discussion on
how to communicate the event-thread death to request-handler-thread.

Thanks to "Karan Sandha"<ksandha@redhat.com> for voluntarily running
the perf benchmarks to qualify that performance regression introduced
by ping-timer-fixes is fixed with this patch and patiently running
many iterations of regression tests while RCAing the issue.

Thanks to "Milind Changire"<mchangir@redhat.com> for patiently running
the many iterations of perf benchmarking tests while RCAing the
regression caused by ping-timer-expiry fixes.

Change-Id: I578c3fc67713f4234bd3abbec5d3fbba19059ea5
Fixes: bz#1644629
Signed-off-by: Raghavendra Gowdappa <rgowdapp@redhat.com>

1 files changed, 14 insertions, 5 deletions

diff --git a/libglusterfs/src/gf-event.h b/libglusterfs/src/gf-event.h
index 5c3724cc953..5d92a2dd285 100644
--- a/libglusterfs/src/gf-event.h
+++ b/libglusterfs/src/gf-event.h
@@ -12,6 +12,7 @@
 #define _GF_EVENT_H_
 
 #include <pthread.h>
+#include "list.h"
 
 struct event_pool;
 struct event_ops;
@@ -23,7 +24,8 @@ struct event_data {
 } __attribute__((__packed__, __may_alias__));
 
 typedef int (*event_handler_t)(int fd, int idx, int gen, void *data,
-                               int poll_in, int poll_out, int poll_err);
+                               int poll_in, int poll_out, int poll_err,
+                               char event_thread_exit);
 
 #define EVENT_EPOLL_TABLES 1024
 #define EVENT_EPOLL_SLOTS 1024
@@ -40,6 +42,13 @@ struct event_pool {
     struct event_slot_epoll *ereg[EVENT_EPOLL_TABLES];
     int slots_used[EVENT_EPOLL_TABLES];
 
+    struct list_head poller_death;
+    int poller_death_sliced; /* track whether the list of fds interested
+                              * poller_death is sliced. If yes, new thread death
+                              * notification has to wait till the list is added
+                              * back
+                              */
+    int poller_gen;
     int used;
     int changed;
 
@@ -52,8 +61,8 @@ struct event_pool {
     /* NOTE: Currently used only when event processing is done using
      * epoll. */
     int eventthreadcount; /* number of event threads to execute. */
-    pthread_t pollers[EVENT_MAX_THREADS]; /* poller thread_id store,
-                                           * and live status */
+    pthread_t pollers[EVENT_MAX_THREADS]; /* poller thread_id store, and live
+                                             status */
     int destroy;
     int activethreadcount;
 
@@ -81,7 +90,7 @@ struct event_ops {
 
     int (*event_register)(struct event_pool *event_pool, int fd,
                           event_handler_t handler, void *data, int poll_in,
-                          int poll_out);
+                          int poll_out, char notify_poller_death);
 
     int (*event_select_on)(struct event_pool *event_pool, int fd, int idx,
                            int poll_in, int poll_out);
@@ -107,7 +116,7 @@ event_select_on(struct event_pool *event_pool, int fd, int idx, int poll_in,
                 int poll_out);
 int
 event_register(struct event_pool *event_pool, int fd, event_handler_t handler,
-               void *data, int poll_in, int poll_out);
+               void *data, int poll_in, int poll_out, char notify_poller_death);
 int
 event_unregister(struct event_pool *event_pool, int fd, int idx);
 int