Merge pull request #12343 from sreecha/enable-epoll1

Enable epoll1 polling engine

src/core/lib/iomgr/ev_epoll1_linux.c

@@ -1192,10 +1192,6 @@ static const grpc_event_engine_vtable vtable = {
  * Create epoll_fd (epoll_set_init() takes care of that) to make sure epoll
  * support is available */
 const grpc_event_engine_vtable *grpc_init_epoll1_linux(bool explicit_request) {
-  if (!explicit_request) {
-    return NULL;
-  }
-
   if (!grpc_has_wakeup_fd()) {
     return NULL;
   }

src/core/lib/iomgr/ev_epollsig_linux.c

@@ -1728,9 +1728,7 @@ const grpc_event_engine_vtable *grpc_init_epollsig_linux(
   }
 
   if (!is_grpc_wakeup_signal_initialized) {
-    /* TODO(ctiller): when other epoll engines are ready, remove the true || to
-     * force this to be explitly chosen if needed */
-    if (true || explicit_request) {
+    if (explicit_request) {
       grpc_use_signal(SIGRTMIN + 6);
     } else {
       return NULL;

src/core/lib/iomgr/ev_posix.c

@@ -64,8 +64,8 @@ typedef struct {
 } event_engine_factory;
 
 static const event_engine_factory g_factories[] = {
-    {"epollsig", grpc_init_epollsig_linux},
     {"epoll1", grpc_init_epoll1_linux},
+    {"epollsig", grpc_init_epollsig_linux},
     {"epoll-threadpool", grpc_init_epoll_thread_pool_linux},
     {"epoll-limited", grpc_init_epoll_limited_pollers_linux},
     {"poll", grpc_init_poll_posix},

tools/run_tests/performance/scenario_config.py

@@ -154,6 +154,8 @@ def _ping_pong_scenario(name, rpc_type,
 
   scenario['client_config']['payload_config'] = _payload_type(use_generic_payload, req_size, resp_size)
 
+  # Optimization target of 'throughput' does not work well with epoll1 polling
+  # engine. Use the default value of 'blend'
   optimization_target = 'blend'
 
   if unconstrained_client:
@@ -169,12 +171,10 @@ def _ping_pong_scenario(name, rpc_type,
     scenario['client_config']['outstanding_rpcs_per_channel'] = deep
     scenario['client_config']['client_channels'] = wide
     scenario['client_config']['async_client_threads'] = 0
-    optimization_target = 'throughput'
   else:
     scenario['client_config']['outstanding_rpcs_per_channel'] = 1
     scenario['client_config']['client_channels'] = 1
     scenario['client_config']['async_client_threads'] = 1
-    optimization_target = 'latency'
 
   optimization_channel_arg = {
     'name': 'grpc.optimization_target',