The patch titled
[PATCH] ipc/sem.c: cacheline align the ipc spinlock for semaphores
has been added to the -mm tree. Its filename is
ipc-semc-cacheline-align-the-ipc-spinlock-for-semaphores.patch
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------------------------------------------------------
Subject: [PATCH] ipc/sem.c: cacheline align the ipc spinlock for semaphores
From: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
This patch cacheline aligns the spinlock for sysv semaphores: Without the
patch, the spinlock and sem_otime [written by every semop that modified
the array] and sem_base [read in the hot path of try_atomic_semop()] can
be in the same cacheline.
Signed-off-by: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Cc: Chris Mason <chris.mason@xxxxxxxxxx>
Cc: Zach Brown <zach.brown@xxxxxxxxxx>
Cc: Jens Axboe <jens.axboe@xxxxxxxxxx>
Cc: Nick Piggin <npiggin@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/sem.h | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff -puN include/linux/sem.h~ipc-semc-cacheline-align-the-ipc-spinlock-for-semaphores include/linux/sem.h
--- a/include/linux/sem.h~ipc-semc-cacheline-align-the-ipc-spinlock-for-semaphores
+++ a/include/linux/sem.h
@@ -79,6 +79,7 @@ struct seminfo {
#ifdef __KERNEL__
#include <asm/atomic.h>
#include <linux/rcupdate.h>
+#include <linux/cache.h>
struct task_struct;
@@ -91,7 +92,8 @@ struct sem {
/* One sem_array data structure for each set of semaphores in the system. */
struct sem_array {
- struct kern_ipc_perm sem_perm; /* permissions .. see ipc.h */
+ struct kern_ipc_perm ____cacheline_aligned_in_smp
+ sem_perm; /* permissions .. see ipc.h */
time_t sem_otime; /* last semop time */
time_t sem_ctime; /* last change time */
struct sem *sem_base; /* ptr to first semaphore in array */
_
Patches currently in -mm which might be from manfred@xxxxxxxxxxxxxxxx are
ipc-semc-optimize-update_queue-for-bulk-wakeup-calls.patch
ipc-semc-optimize-update_queue-for-bulk-wakeup-calls-fix.patch
ipc-semc-move-wake_up_process-out-of-the-spinlock-section.patch
ipc-semc-move-wake_up_process-out-of-the-spinlock-section-fix.patch
ipc-semc-cacheline-align-the-ipc-spinlock-for-semaphores.patch
slab-leaks3-default-y.patch
--
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