The patch titled
Subject: slub: create new ___slab_alloc function that can be called with irqs disabled
has been added to the -mm tree. Its filename is
slub-create-new-___slab_alloc-function-that-can-be-called-with-irqs-disabled.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/slub-create-new-___slab_alloc-function-that-can-be-called-with-irqs-disabled.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/slub-create-new-___slab_alloc-function-that-can-be-called-with-irqs-disabled.patch
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------------------------------------------------------
From: Christoph Lameter <cl@xxxxxxxxx>
Subject: slub: create new ___slab_alloc function that can be called with irqs disabled
Bulk alloc needs a function like that because it enables interrupts before
calling __slab_alloc which promptly disables them again using the expensive
local_irq_save().
Signed-off-by: Christoph Lameter <cl@xxxxxxxxx>
Cc: Jesper Dangaard Brouer <brouer@xxxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/slub.c | 44 +++++++++++++++++++++++++++++---------------
1 file changed, 29 insertions(+), 15 deletions(-)
diff -puN mm/slub.c~slub-create-new-___slab_alloc-function-that-can-be-called-with-irqs-disabled mm/slub.c
--- a/mm/slub.c~slub-create-new-___slab_alloc-function-that-can-be-called-with-irqs-disabled
+++ a/mm/slub.c
@@ -2298,23 +2298,15 @@ static inline void *get_freelist(struct
* And if we were unable to get a new slab from the partial slab lists then
* we need to allocate a new slab. This is the slowest path since it involves
* a call to the page allocator and the setup of a new slab.
+ *
+ * Version of __slab_alloc to use when we know that interrupts are
+ * already disabled (which is the case for bulk allocation).
*/
-static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
+static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
unsigned long addr, struct kmem_cache_cpu *c)
{
void *freelist;
struct page *page;
- unsigned long flags;
-
- local_irq_save(flags);
-#ifdef CONFIG_PREEMPT
- /*
- * We may have been preempted and rescheduled on a different
- * cpu before disabling interrupts. Need to reload cpu area
- * pointer.
- */
- c = this_cpu_ptr(s->cpu_slab);
-#endif
page = c->page;
if (!page)
@@ -2372,7 +2364,6 @@ load_freelist:
VM_BUG_ON(!c->page->frozen);
c->freelist = get_freepointer(s, freelist);
c->tid = next_tid(c->tid);
- local_irq_restore(flags);
return freelist;
new_slab:
@@ -2389,7 +2380,6 @@ new_slab:
if (unlikely(!freelist)) {
slab_out_of_memory(s, gfpflags, node);
- local_irq_restore(flags);
return NULL;
}
@@ -2405,11 +2395,35 @@ new_slab:
deactivate_slab(s, page, get_freepointer(s, freelist));
c->page = NULL;
c->freelist = NULL;
- local_irq_restore(flags);
return freelist;
}
/*
+ * Another one that disabled interrupt and compensates for possible
+ * cpu changes by refetching the per cpu area pointer.
+ */
+static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
+ unsigned long addr, struct kmem_cache_cpu *c)
+{
+ void *p;
+ unsigned long flags;
+
+ local_irq_save(flags);
+#ifdef CONFIG_PREEMPT
+ /*
+ * We may have been preempted and rescheduled on a different
+ * cpu before disabling interrupts. Need to reload cpu area
+ * pointer.
+ */
+ c = this_cpu_ptr(s->cpu_slab);
+#endif
+
+ p = ___slab_alloc(s, gfpflags, node, addr, c);
+ local_irq_restore(flags);
+ return p;
+}
+
+/*
* Inlined fastpath so that allocation functions (kmalloc, kmem_cache_alloc)
* have the fastpath folded into their functions. So no function call
* overhead for requests that can be satisfied on the fastpath.
_
Patches currently in -mm which might be from cl@xxxxxxxxx are
slub-create-new-___slab_alloc-function-that-can-be-called-with-irqs-disabled.patch
slub-avoid-irqoff-on-in-bulk-allocation.patch
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