From 0858590216ba36cd5e4f69be84f643fd00a85e87 Mon Sep 17 00:00:00 2001
From: Konstantin Osipov <kostja@tarantool.org>
Date: Mon, 2 Feb 2015 15:16:51 +0300
Subject: [PATCH] Add a fiber benchmark.
Remove explicit fiber call stack from the cord.
Fix backtrace() to work correclty with an optimized (-O2) build.
---
src/fiber.cc | 15 ++++++++-------
src/fiber.h | 14 +++++++-------
src/util.cc | 17 ++++++++++++++---
test/unit/fiber.cc | 32 ++++++++++++++++++++++++++++++++
4 files changed, 61 insertions(+), 17 deletions(-)
diff --git a/src/fiber.cc b/src/fiber.cc
index d1d64f6d1e..c396d240e5 100644
--- a/src/fiber.cc
+++ b/src/fiber.cc
@@ -58,16 +58,16 @@ fiber_call(struct fiber *callee)
struct fiber *caller = fiber();
struct cord *cord = cord();
- assert(cord->sp + 1 - cord->stack < FIBER_CALL_STACK);
+ assert(cord->call_stack_depth < FIBER_CALL_STACK);
assert(caller);
+ cord->call_stack_depth++;
cord->fiber = callee;
- *cord->sp++ = caller;
+ callee->caller = caller;
update_last_stack_frame(caller);
callee->csw++;
-
coro_transfer(&caller->coro.ctx, &callee->coro.ctx);
}
@@ -82,8 +82,7 @@ fiber_start(struct fiber *callee, ...)
bool
fiber_checkstack()
{
- struct cord *cord = cord();
- if (cord->sp + 1 - cord->stack >= FIBER_CALL_STACK)
+ if (cord()->call_stack_depth + 1 >= FIBER_CALL_STACK)
return true;
return false;
}
@@ -192,8 +191,10 @@ void
fiber_yield(void)
{
struct cord *cord = cord();
- struct fiber *callee = *(--cord->sp);
struct fiber *caller = cord->fiber;
+ struct fiber *callee = caller->caller;
+ cord->call_stack_depth--;
+ caller->caller = &cord->sched;
/** By convention, these triggers must not throw. */
if (! rlist_empty(&caller->on_yield))
@@ -413,6 +414,7 @@ fiber_new(const char *name, void (*f) (va_list))
region_create(&fiber->gc, &cord->slabc);
rlist_add_entry(&cord->fibers, fiber, link);
+ fiber->caller = &cord->sched;
}
fiber->f = f;
@@ -483,7 +485,6 @@ cord_create(struct cord *cord, const char *name)
region_create(&cord->sched.gc, &cord->slabc);
fiber_set_name(&cord->sched, "sched");
- cord->sp = cord->stack;
cord->max_fid = 100;
Exception::init(cord);
diff --git a/src/fiber.h b/src/fiber.h
index ecb332166b..d78dcbaac8 100644
--- a/src/fiber.h
+++ b/src/fiber.h
@@ -101,6 +101,11 @@ struct fiber {
#ifdef ENABLE_BACKTRACE
void *last_stack_frame;
#endif
+ /**
+ * The fiber which should be scheduled when
+ * this fiber yields.
+ */
+ struct fiber *caller;
int csw;
struct tarantool_coro coro;
/* A garbage-collected memory pool. */
@@ -145,13 +150,8 @@ struct cord {
/** The "main" fiber of this cord, the scheduler. */
struct fiber sched;
struct ev_loop *loop;
- /** Call stack - in case one fiber decides to call
- * another with fiber_call(). This is not used
- * currently, all fibers are called by the sched
- */
- struct fiber *stack[FIBER_CALL_STACK];
- /** Stack pointer in fiber call stack. */
- struct fiber **sp;
+ /** Depth of the fiber call stack. */
+ int call_stack_depth;
/**
* Every new fiber gets a new monotonic id. Ids 1-100 are
* reserved.
diff --git a/src/util.cc b/src/util.cc
index 84c021b48b..0e2165f650 100644
--- a/src/util.cc
+++ b/src/util.cc
@@ -231,7 +231,8 @@ fmemopen(void *buf, size_t size, const char *mode)
static char backtrace_buf[4096 * 4];
/*
- * note, stack unwinding code assumes that binary is compiled with frame pointers
+ * note, stack unwinding code assumes that binary is compiled with
+ * frame pointers
*/
struct frame {
@@ -250,6 +251,11 @@ backtrace(void *frame_, void *stack, size_t stack_size)
char *end = p + sizeof(backtrace_buf) - 1;
int frameno = 0;
while (stack_bottom <= (void *)frame && (void *)frame < stack_top) {
+ /**
+ * The stack may be overwritten by the callback
+ * in case of optimized builds.
+ */
+ struct frame *prev_frame = frame->rbp;
p += snprintf(p, end - p, "#%-2d %p in ", frameno++, frame->ret);
if (p >= end)
@@ -275,7 +281,7 @@ backtrace(void *frame_, void *stack, size_t stack_size)
break;
#endif
- frame = frame->rbp;
+ frame = prev_frame;
}
out:
*p = '\0';
@@ -293,6 +299,11 @@ backtrace_foreach(backtrace_cb cb, void *frame_, void *stack, size_t stack_size,
const char *sym = NULL;
size_t offset = 0;
while (stack_bottom <= (void *)frame && (void *)frame < stack_top) {
+ /**
+ * The stack may be overwritten by the callback
+ * in case of optimized builds.
+ */
+ struct frame *prev_frame = frame->rbp;
#ifdef HAVE_BFD
struct symbol *s = addr2symbol(frame->ret);
if (s != NULL) {
@@ -307,7 +318,7 @@ backtrace_foreach(backtrace_cb cb, void *frame_, void *stack, size_t stack_size,
int rc = cb(frameno, frame->ret, sym, offset, cb_ctx);
if (rc != 0)
return;
- frame = frame->rbp;
+ frame = prev_frame;
sym = NULL;
offset = 0;
frameno++;
diff --git a/test/unit/fiber.cc b/test/unit/fiber.cc
index d851007323..1672b3be54 100644
--- a/test/unit/fiber.cc
+++ b/test/unit/fiber.cc
@@ -1,9 +1,41 @@
#include "memory.h"
#include "fiber.h"
+
+enum {
+ ITERATIONS = 5000,
+ FIBERS = 10
+};
+
+void yield_f(va_list ap)
+{
+ for (int i = 0; i < ITERATIONS; i++) {
+ fiber_wakeup(fiber());
+ fiber_yield();
+ }
+}
+
+void benchmark_f(va_list ap)
+{
+ struct fiber *fibers[FIBERS];
+ for (int i = 0; i < FIBERS; i++) {
+ fibers[i] = fiber_new("yield-wielder", yield_f);
+ fiber_wakeup(fibers[i]);
+ }
+ /** Wait for fibers to die. */
+ for (int i = 0; i < FIBERS; i++) {
+ while (fibers[i]->fid > 0)
+ fiber_sleep(0.001);
+ }
+ ev_break(loop(), EVBREAK_ALL);
+}
+
int main()
{
memory_init();
fiber_init();
+ struct fiber *benchmark = fiber_new("benchmark", benchmark_f);
+ fiber_wakeup(benchmark);
+ ev_run(loop(), 0);
fiber_free();
memory_free();
return 0;
--
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