SLUB: Introduce and use SLUB_MAX_SIZE and SLUB_PAGE_SHIFT constants
As a preparational patch to bump up page allocator pass-through threshold, introduce two new constants SLUB_MAX_SIZE and SLUB_PAGE_SHIFT and convert mm/slub.c to use them. Reported-by: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com> Tested-by: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com> Signed-off-by: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
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Pekka Enberg

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@@ -120,11 +120,24 @@ struct kmem_cache {
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#define KMALLOC_SHIFT_LOW ilog2(KMALLOC_MIN_SIZE)
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/*
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* Maximum kmalloc object size handled by SLUB. Larger object allocations
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* are passed through to the page allocator. The page allocator "fastpath"
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* is relatively slow so we need this value sufficiently high so that
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* performance critical objects are allocated through the SLUB fastpath.
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*
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* This should be dropped to PAGE_SIZE / 2 once the page allocator
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* "fastpath" becomes competitive with the slab allocator fastpaths.
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*/
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#define SLUB_MAX_SIZE (PAGE_SIZE)
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#define SLUB_PAGE_SHIFT (PAGE_SHIFT + 1)
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/*
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* We keep the general caches in an array of slab caches that are used for
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* 2^x bytes of allocations.
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*/
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extern struct kmem_cache kmalloc_caches[PAGE_SHIFT + 1];
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extern struct kmem_cache kmalloc_caches[SLUB_PAGE_SHIFT];
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/*
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* Sorry that the following has to be that ugly but some versions of GCC
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@@ -212,7 +225,7 @@ static __always_inline void *kmalloc_large(size_t size, gfp_t flags)
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static __always_inline void *kmalloc(size_t size, gfp_t flags)
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{
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if (__builtin_constant_p(size)) {
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if (size > PAGE_SIZE)
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if (size > SLUB_MAX_SIZE)
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return kmalloc_large(size, flags);
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if (!(flags & SLUB_DMA)) {
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@@ -234,7 +247,7 @@ void *kmem_cache_alloc_node(struct kmem_cache *, gfp_t flags, int node);
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static __always_inline void *kmalloc_node(size_t size, gfp_t flags, int node)
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{
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if (__builtin_constant_p(size) &&
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size <= PAGE_SIZE && !(flags & SLUB_DMA)) {
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size <= SLUB_MAX_SIZE && !(flags & SLUB_DMA)) {
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struct kmem_cache *s = kmalloc_slab(size);
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if (!s)
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