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.
Signed-off-by: Kirill A. Shutemov <[email protected]> --- lib/radix-tree.c | 27 ++++++++++++++++----------- 1 file changed, 16 insertions(+), 11 deletions(-) diff --git a/lib/radix-tree.c b/lib/radix-tree.c index 3d2aa27b845b..1f58724a2f58 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 prealocated 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--; } /* @@ -257,16 +259,18 @@ 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; @@ -1463,15 +1467,16 @@ 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; -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
