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| author | Kirill A. Shutemov <kirill.shutemov@linux.intel.com> | 2015-06-25 15:02:19 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-06-25 17:00:40 -0700 |
| commit | 9d2a8da006fcbf2dea663c095f0a0088dfbbec15 (patch) | |
| tree | 822753e767183c408f675b3f274a0c6601102727 /lib/radix-tree.c | |
| parent | 9cf79d115f0d161b63161650f14ff903e4c57937 (diff) | |
| download | linux-9d2a8da006fcbf2dea663c095f0a0088dfbbec15.tar.gz linux-9d2a8da006fcbf2dea663c095f0a0088dfbbec15.tar.bz2 linux-9d2a8da006fcbf2dea663c095f0a0088dfbbec15.zip | |
radix-tree: replace preallocated node array with linked list
Currently we use per-cpu array to hold pointers to preallocated nodes.
Let's replace it with linked list. On x86_64 it saves 256 bytes in
per-cpu ELF section which may translate into freeing up 2MB of memory for
NR_CPUS==8192.
[akpm@linux-foundation.org: fix comment, coding style]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib/radix-tree.c')
| -rw-r--r-- | lib/radix-tree.c | 28 |
1 files changed, 17 insertions, 11 deletions
diff --git a/lib/radix-tree.c b/lib/radix-tree.c index 061550de77bc..f9ebe1c82060 100644 --- a/lib/radix-tree.c +++ b/lib/radix-tree.c @@ -65,7 +65,8 @@ static struct kmem_cache *radix_tree_node_cachep; */ struct radix_tree_preload { int nr; - struct radix_tree_node *nodes[RADIX_TREE_PRELOAD_SIZE]; + /* nodes->private_data points to next preallocated node */ + struct radix_tree_node *nodes; }; static DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, }; @@ -197,8 +198,9 @@ radix_tree_node_alloc(struct radix_tree_root *root) */ rtp = this_cpu_ptr(&radix_tree_preloads); if (rtp->nr) { - ret = rtp->nodes[rtp->nr - 1]; - rtp->nodes[rtp->nr - 1] = NULL; + ret = rtp->nodes; + rtp->nodes = ret->private_data; + ret->private_data = NULL; rtp->nr--; } /* @@ -257,17 +259,20 @@ static int __radix_tree_preload(gfp_t gfp_mask) preempt_disable(); rtp = this_cpu_ptr(&radix_tree_preloads); - while (rtp->nr < ARRAY_SIZE(rtp->nodes)) { + while (rtp->nr < RADIX_TREE_PRELOAD_SIZE) { preempt_enable(); node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask); if (node == NULL) goto out; preempt_disable(); rtp = this_cpu_ptr(&radix_tree_preloads); - if (rtp->nr < ARRAY_SIZE(rtp->nodes)) - rtp->nodes[rtp->nr++] = node; - else + if (rtp->nr < RADIX_TREE_PRELOAD_SIZE) { + node->private_data = rtp->nodes; + rtp->nodes = node; + rtp->nr++; + } else { kmem_cache_free(radix_tree_node_cachep, node); + } } ret = 0; out: @@ -1463,15 +1468,16 @@ static int radix_tree_callback(struct notifier_block *nfb, { int cpu = (long)hcpu; struct radix_tree_preload *rtp; + struct radix_tree_node *node; /* Free per-cpu pool of perloaded nodes */ if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) { rtp = &per_cpu(radix_tree_preloads, cpu); while (rtp->nr) { - kmem_cache_free(radix_tree_node_cachep, - rtp->nodes[rtp->nr-1]); - rtp->nodes[rtp->nr-1] = NULL; - rtp->nr--; + node = rtp->nodes; + rtp->nodes = node->private_data; + kmem_cache_free(radix_tree_node_cachep, node); + rtp->nr--; } } return NOTIFY_OK; |