[PATCH] spinlock_debug: don't recompute (jiffies_per_loop * HZ) in spinloop
In spinlock_debug.c, the spinloops call __delay() on every iteration.
Because that is an external function, (jiffies_per_loop * HZ), the loop's
iteration limit, gets recomputed every time. Caching it explicitly
prevents that.
Signed-off-by: Chuck Ebbert <76306.1226@compuserve.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/lib/spinlock_debug.c b/lib/spinlock_debug.c
index 58c577d..dafaf1d 100644
--- a/lib/spinlock_debug.c
+++ b/lib/spinlock_debug.c
@@ -99,11 +99,12 @@
static void __spin_lock_debug(spinlock_t *lock)
{
- int print_once = 1;
u64 i;
+ u64 loops = loops_per_jiffy * HZ;
+ int print_once = 1;
for (;;) {
- for (i = 0; i < loops_per_jiffy * HZ; i++) {
+ for (i = 0; i < loops; i++) {
if (__raw_spin_trylock(&lock->raw_lock))
return;
__delay(1);
@@ -165,11 +166,12 @@
#if 0 /* __write_lock_debug() can lock up - maybe this can too? */
static void __read_lock_debug(rwlock_t *lock)
{
- int print_once = 1;
u64 i;
+ u64 loops = loops_per_jiffy * HZ;
+ int print_once = 1;
for (;;) {
- for (i = 0; i < loops_per_jiffy * HZ; i++) {
+ for (i = 0; i < loops; i++) {
if (__raw_read_trylock(&lock->raw_lock))
return;
__delay(1);
@@ -239,11 +241,12 @@
#if 0 /* This can cause lockups */
static void __write_lock_debug(rwlock_t *lock)
{
- int print_once = 1;
u64 i;
+ u64 loops = loops_per_jiffy * HZ;
+ int print_once = 1;
for (;;) {
- for (i = 0; i < loops_per_jiffy * HZ; i++) {
+ for (i = 0; i < loops; i++) {
if (__raw_write_trylock(&lock->raw_lock))
return;
__delay(1);