The patch titled
spinlock_debug: don't recompute (jiffies_per_loop applied-patches arch backup bin block config-x COPYING CREDITS CREDITS~git-gfs2 crypto CVS Documentation drivers fs include init ipc Kbuild kernel lib linus-series log mach MAINTAINERS MAINTAINERS~avr32-arch MAINTAINERS~edac-new-opteron-athlon64-memory-controller-driver MAINTAINERS~git-gfs2 MAINTAINERS~git-klibc MAINTAINERS.orig MAINTAINERS~origin MAINTAINERS~qla3xxx-NIC-driver MAINTAINERS~x86_64-mm-add-a-maintainers-entry-for-calgary Makefile Makefile~git-kbuild Makefile~git-klibc Makefile~mm Makefile.orig Makefile.rej mm net notes patches pc README REPORTING-BUGS scripts security series 'series sound Tags test.img txt usr HZ) in spinloop
has been added to the -mm tree. Its filename is
spinlock_debug-dont-recompute-jiffies_per_loop.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: spinlock_debug: don't recompute (jiffies_per_loop applied-patches arch backup bin block config-x COPYING CREDITS CREDITS~git-gfs2 crypto CVS Documentation drivers fs include init ipc Kbuild kernel lib linus-series log mach MAINTAINERS MAINTAINERS~avr32-arch MAINTAINERS~edac-new-opteron-athlon64-memory-controller-driver MAINTAINERS~git-gfs2 MAINTAINERS~git-klibc MAINTAINERS.orig MAINTAINERS~origin MAINTAINERS~qla3xxx-NIC-driver MAINTAINERS~x86_64-mm-add-a-maintainers-entry-for-calgary Makefile Makefile~git-kbuild Makefile~git-klibc Makefile~mm Makefile.orig Makefile.rej mm net notes patches pc README REPORTING-BUGS scripts security series 'series sound Tags test.img txt usr HZ) in spinloop
From: Chuck Ebbert <76306.1226@xxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
lib/spinlock_debug.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff -puN lib/spinlock_debug.c~spinlock_debug-dont-recompute-jiffies_per_loop lib/spinlock_debug.c
--- a/lib/spinlock_debug.c~spinlock_debug-dont-recompute-jiffies_per_loop
+++ a/lib/spinlock_debug.c
@@ -99,11 +99,12 @@ static inline void debug_spin_unlock(spi
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 @@ static void rwlock_bug(rwlock_t *lock, c
#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 @@ static inline void debug_write_unlock(rw
#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);
_
Patches currently in -mm which might be from 76306.1226@xxxxxxxxxxxxxx are
ieee80211-tkip-requires-crc32.patch
i386-print-stack-size-in-oops-messages.patch
sleazy-fpu-feature-i386-support.patch
i386-early-fault-handler.patch
i386-fix-recursive-faults-during-oops-when-current.patch
i386-show_registers-try-harder-to-print-failing.patch
spinlock_debug-dont-recompute-jiffies_per_loop.patch
-
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