diff options
| author | Jesper Dangaard Brouer <brouer@redhat.com> | 2015-09-05 01:45:40 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-09-05 02:54:41 +0300 |
| commit | ebe909e0fdb34b980c5cf636c495e4f0bb0dfda8 (patch) | |
| tree | 2087cea54da9f5f7868cc18d2a7b442de01d7e31 /mm/slub.c | |
| parent | 994eb764ec5ad57c9b7c5e72b892205039a84b69 (diff) | |
| download | linux-ebe909e0fdb34b980c5cf636c495e4f0bb0dfda8.tar.xz | |
slub: improve bulk alloc strategy
Call slowpath __slab_alloc() from within the bulk loop, as the side-effect
of this call likely repopulates c->freelist.
Choose to reenable local IRQs while calling slowpath.
Saving some optimizations for later. E.g. it is possible to extract
parts of __slab_alloc() and avoid the unnecessary and expensive (37
cycles) local_irq_{save,restore}. For now, be happy calling
__slab_alloc() this lower icache impact of this func and I don't have to
worry about correctness.
Measurements on CPU CPU i7-4790K @ 4.00GHz
Baseline normal fastpath (alloc+free cost): 42 cycles(tsc) 10.601 ns
Bulk- fallback - this-patch
1 - 58 cycles(tsc) 14.516 ns - 49 cycles(tsc) 12.459 ns improved 15.5%
2 - 51 cycles(tsc) 12.930 ns - 38 cycles(tsc) 9.605 ns improved 25.5%
3 - 49 cycles(tsc) 12.274 ns - 34 cycles(tsc) 8.525 ns improved 30.6%
4 - 48 cycles(tsc) 12.058 ns - 32 cycles(tsc) 8.036 ns improved 33.3%
8 - 46 cycles(tsc) 11.609 ns - 31 cycles(tsc) 7.756 ns improved 32.6%
16 - 45 cycles(tsc) 11.451 ns - 32 cycles(tsc) 8.148 ns improved 28.9%
30 - 79 cycles(tsc) 19.865 ns - 68 cycles(tsc) 17.164 ns improved 13.9%
32 - 76 cycles(tsc) 19.212 ns - 66 cycles(tsc) 16.584 ns improved 13.2%
34 - 74 cycles(tsc) 18.600 ns - 63 cycles(tsc) 15.954 ns improved 14.9%
48 - 88 cycles(tsc) 22.092 ns - 77 cycles(tsc) 19.373 ns improved 12.5%
64 - 80 cycles(tsc) 20.043 ns - 68 cycles(tsc) 17.188 ns improved 15.0%
128 - 99 cycles(tsc) 24.818 ns - 89 cycles(tsc) 22.404 ns improved 10.1%
158 - 99 cycles(tsc) 24.977 ns - 92 cycles(tsc) 23.089 ns improved 7.1%
250 - 106 cycles(tsc) 26.552 ns - 99 cycles(tsc) 24.785 ns improved 6.6%
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/slub.c')
| -rw-r--r-- | mm/slub.c | 26 |
1 files changed, 16 insertions, 10 deletions
diff --git a/mm/slub.c b/mm/slub.c index 30e7dedec664..f98b1b9e7080 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2779,8 +2779,22 @@ bool kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size, for (i = 0; i < size; i++) { void *object = c->freelist; - if (!object) - break; + if (unlikely(!object)) { + local_irq_enable(); + /* + * Invoking slow path likely have side-effect + * of re-populating per CPU c->freelist + */ + p[i] = __slab_alloc(s, flags, NUMA_NO_NODE, + _RET_IP_, c); + if (unlikely(!p[i])) { + __kmem_cache_free_bulk(s, i, p); + return false; + } + local_irq_disable(); + c = this_cpu_ptr(s->cpu_slab); + continue; /* goto for-loop */ + } c->freelist = get_freepointer(s, object); p[i] = object; @@ -2796,14 +2810,6 @@ bool kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size, memset(p[j], 0, s->object_size); } - /* Fallback to single elem alloc */ - for (; i < size; i++) { - void *x = p[i] = kmem_cache_alloc(s, flags); - if (unlikely(!x)) { - __kmem_cache_free_bulk(s, i, p); - return false; - } - } return true; } EXPORT_SYMBOL(kmem_cache_alloc_bulk); |