The patch titled
Subject: mm, slub: Use prefetchw instead of prefetch
has been added to the -mm tree. Its filename is
mm-slub-use-prefetchw-instead-of-prefetch.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-slub-use-prefetchw-instead-of-prefetch.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-slub-use-prefetchw-instead-of-prefetch.patch
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------------------------------------------------------
From: Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx>
Subject: mm, slub: Use prefetchw instead of prefetch
It's certain that an object will be not only read, but also written after
allocation.
Use prefetchw instead of prefetch. On supported architectures like x86,
it helps to invalidate cache line when the object exists in other
processors' cache.
Link: https://lkml.kernel.org/r/20211008133602.4963-1-42.hyeyoo@xxxxxxxxx
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/slub.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
--- a/mm/slub.c~mm-slub-use-prefetchw-instead-of-prefetch
+++ a/mm/slub.c
@@ -352,9 +352,9 @@ static inline void *get_freepointer(stru
return freelist_dereference(s, object + s->offset);
}
-static void prefetch_freepointer(const struct kmem_cache *s, void *object)
+static void prefetchw_freepointer(const struct kmem_cache *s, void *object)
{
- prefetch(object + s->offset);
+ prefetchw(object + s->offset);
}
static inline void *get_freepointer_safe(struct kmem_cache *s, void *object)
@@ -3202,10 +3202,9 @@ redo:
note_cmpxchg_failure("slab_alloc", s, tid);
goto redo;
}
- prefetch_freepointer(s, next_object);
+ prefetchw_freepointer(s, next_object);
stat(s, ALLOC_FASTPATH);
}
-
maybe_wipe_obj_freeptr(s, object);
init = slab_want_init_on_alloc(gfpflags, s);
_
Patches currently in -mm which might be from 42.hyeyoo@xxxxxxxxx are
mm-slub-use-prefetchw-instead-of-prefetch.patch
