Subject: [merged] ipc-semc-cacheline-align-the-semaphore-structures.patch removed from -mm tree To: manfred@xxxxxxxxxxxxxxxx,davidlohr.bueso@xxxxxx,riel@xxxxxxxxxx,mm-commits@xxxxxxxxxxxxxxx From: akpm@xxxxxxxxxxxxxxxxxxxx Date: Tue, 09 Jul 2013 16:21:53 -0700 The patch titled Subject: ipc/sem.c: cacheline align the semaphore structures has been removed from the -mm tree. Its filename was ipc-semc-cacheline-align-the-semaphore-structures.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx> Subject: ipc/sem.c: cacheline align the semaphore structures As now each semaphore has its own spinlock and parallel operations are possible, give each semaphore its own cacheline. On a i3 laptop, this gives up to 28% better performance: #semscale 10 | grep "interleave 2" - before: Cpus 1, interleave 2 delay 0: 36109234 in 10 secs Cpus 2, interleave 2 delay 0: 55276317 in 10 secs Cpus 3, interleave 2 delay 0: 62411025 in 10 secs Cpus 4, interleave 2 delay 0: 81963928 in 10 secs -after: Cpus 1, interleave 2 delay 0: 35527306 in 10 secs Cpus 2, interleave 2 delay 0: 70922909 in 10 secs <<< + 28% Cpus 3, interleave 2 delay 0: 80518538 in 10 secs Cpus 4, interleave 2 delay 0: 89115148 in 10 secs <<< + 8.7% i3, with 2 cores and with hyperthreading enabled. Interleave 2 in order use first the full cores. HT partially hides the delay from cacheline trashing, thus the improvement is "only" 8.7% if 4 threads are running. Signed-off-by: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxx> Cc: Davidlohr Bueso <davidlohr.bueso@xxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- ipc/sem.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff -puN ipc/sem.c~ipc-semc-cacheline-align-the-semaphore-structures ipc/sem.c --- a/ipc/sem.c~ipc-semc-cacheline-align-the-semaphore-structures +++ a/ipc/sem.c @@ -96,7 +96,7 @@ struct sem { int sempid; /* pid of last operation */ spinlock_t lock; /* spinlock for fine-grained semtimedop */ struct list_head sem_pending; /* pending single-sop operations */ -}; +} ____cacheline_aligned_in_smp; /* One queue for each sleeping process in the system. */ struct sem_queue { _ Patches currently in -mm which might be from manfred@xxxxxxxxxxxxxxxx are origin.patch slab-leaks3-default-y.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html