From 4fe852430f8f78265be1bbc01e897f0d889f6d7e Mon Sep 17 00:00:00 2001
From: Konstantin Osipov <kostja@tarantool.org>
Date: Fri, 20 Mar 2015 17:05:15 +0300
Subject: [PATCH] fiber scheduling: schedule ready fibers more aggressively
If a fiber becomes ready on a user-defined event, schedule it
in the same event loop, not in the next loop, to save one epoll_wait()
invocation in cases when something is added to a fiber channel,
and there is a fiber ready for execution waiting on the channel.
Add a micro-bench to the unit test suite.
---
src/fiber.cc | 18 ++++++-------
test/unit/CMakeLists.txt | 3 +++
test/unit/ipc.cc | 55 ++++++++++++++++++++++++++++++++++++++++
test/unit/ipc.result | 3 +++
4 files changed, 69 insertions(+), 10 deletions(-)
create mode 100644 test/unit/ipc.cc
create mode 100644 test/unit/ipc.result
diff --git a/src/fiber.cc b/src/fiber.cc
index ff02fb3132..111aaca7da 100644
--- a/src/fiber.cc
+++ b/src/fiber.cc
@@ -105,12 +105,12 @@ fiber_wakeup(struct fiber *f)
if (rlist_empty(&cord->ready)) {
/*
* ev_feed_event() is possibly faster,
- * but custom event gets scheduled in the
+ * but EV_CUSTOM event gets scheduled in the
* same event loop iteration, which can
- * produce unfair scheduling (see the case of
+ * produce unfair scheduling, (see the case of
* fiber_sleep(0))
*/
- ev_async_send(cord->loop, &cord->wakeup_event);
+ ev_feed_event(cord->loop, &cord->wakeup_event, EV_CUSTOM);
}
rlist_move_tail_entry(&cord->ready, f, state);
}
@@ -293,13 +293,11 @@ fiber_yield_timeout(ev_tstamp delay)
void
fiber_sleep(ev_tstamp delay)
{
- if (delay == 0) {
- /* Faster than starting and stopping a timer. */
- fiber_wakeup(fiber());
- fiber_yield();
- } else {
- fiber_yield_timeout(delay);
- }
+ /*
+ * We don't use fiber_wakeup() here to ensure there is
+ * no infinite wakeup loop in case of fiber_sleep(0).
+ */
+ fiber_yield_timeout(delay);
fiber_testcancel();
}
diff --git a/test/unit/CMakeLists.txt b/test/unit/CMakeLists.txt
index 1b8d8c0088..4833461371 100644
--- a/test/unit/CMakeLists.txt
+++ b/test/unit/CMakeLists.txt
@@ -65,6 +65,9 @@ target_link_libraries(fiber.test core)
add_executable(fiber_stress.test fiber_stress.cc)
target_link_libraries(fiber_stress.test core)
+add_executable(ipc.test ipc.cc ${CMAKE_SOURCE_DIR}/src/ipc.cc)
+target_link_libraries(ipc.test core)
+
add_executable(coio.test coio.cc unit.c
${CMAKE_SOURCE_DIR}/src/sio.cc
${CMAKE_SOURCE_DIR}/src/evio.cc
diff --git a/test/unit/ipc.cc b/test/unit/ipc.cc
new file mode 100644
index 0000000000..c5812bbf90
--- /dev/null
+++ b/test/unit/ipc.cc
@@ -0,0 +1,55 @@
+#include "memory.h"
+#include "fiber.h"
+#include "ipc.h"
+#include "unit.h"
+
+enum {
+ ITERATIONS = 100000,
+};
+
+void
+push_f(va_list ap)
+{
+ struct ipc_channel *channel = va_arg(ap, struct ipc_channel *);
+
+ for (int i = 0; i < ITERATIONS; i++)
+ ipc_channel_put(channel, NULL);
+}
+
+void
+pop_f(va_list ap)
+{
+ struct ipc_channel *channel = va_arg(ap, struct ipc_channel *);
+
+ for (int i = 0; i < ITERATIONS; i++)
+ (void) ipc_channel_get(channel);
+}
+
+void main_f(va_list ap)
+{
+ header();
+ struct fiber *push = fiber_new("push_f", push_f);
+ fiber_set_joinable(push, true);
+ struct fiber *pop = fiber_new("pop_f", pop_f);
+ fiber_set_joinable(pop, true);
+ struct ipc_channel *channel = ipc_channel_new(1);
+ fiber_start(push, channel);
+ fiber_start(pop, channel);
+ fiber_join(push);
+ fiber_join(pop);
+ ipc_channel_delete(channel);
+ ev_break(loop(), EVBREAK_ALL);
+ footer();
+}
+
+int main()
+{
+ memory_init();
+ fiber_init();
+ struct fiber *main= fiber_new("main", main_f);
+ fiber_wakeup(main);
+ ev_run(loop(), 0);
+ fiber_free();
+ memory_free();
+ return 0;
+}
diff --git a/test/unit/ipc.result b/test/unit/ipc.result
new file mode 100644
index 0000000000..f3398fb9c7
--- /dev/null
+++ b/test/unit/ipc.result
@@ -0,0 +1,3 @@
+ *** main_f ***
+ *** main_f: done ***
+
\ No newline at end of file
--
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