lg_prealloc_list seems to cry out for a per-cpu data structure; on a large
smp system I think this should be better. I've lightly tested this change
on a 4-cpu system. Comments welcome...
Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
---
ndex: linux-2.6/fs/ext4/mballoc.c
===================================================================
--- linux-2.6.orig/fs/ext4/mballoc.c 2008-08-04 15:30:30.000000000 -0500
+++ linux-2.6/fs/ext4/mballoc.c 2008-08-13 13:48:33.224165751 -0500
@@ -2540,17 +2540,16 @@ int ext4_mb_init(struct super_block *sb,
sbi->s_mb_history_filter = EXT4_MB_HISTORY_DEFAULT;
sbi->s_mb_group_prealloc = MB_DEFAULT_GROUP_PREALLOC;
- i = sizeof(struct ext4_locality_group) * nr_cpu_ids;
- sbi->s_locality_groups = kmalloc(i, GFP_KERNEL);
+ sbi->s_locality_groups = alloc_percpu(struct ext4_locality_group);
if (sbi->s_locality_groups == NULL) {
clear_opt(sbi->s_mount_opt, MBALLOC);
kfree(sbi->s_mb_offsets);
kfree(sbi->s_mb_maxs);
return -ENOMEM;
}
- for (i = 0; i < nr_cpu_ids; i++) {
+ for_each_possible_cpu(i) {
struct ext4_locality_group *lg;
- lg = &sbi->s_locality_groups[i];
+ lg = per_cpu_ptr(sbi->s_locality_groups, i);
mutex_init(&lg->lg_mutex);
for (j = 0; j < PREALLOC_TB_SIZE; j++)
INIT_LIST_HEAD(&lg->lg_prealloc_list[j]);
@@ -2647,8 +2646,7 @@ int ext4_mb_release(struct super_block *
atomic_read(&sbi->s_mb_discarded));
}
- kfree(sbi->s_locality_groups);
-
+ free_percpu(sbi->s_locality_groups);
ext4_mb_history_release(sb);
ext4_mb_destroy_per_dev_proc(sb);
@@ -4055,8 +4053,7 @@ static void ext4_mb_group_or_file(struct
* per cpu locality group is to reduce the contention between block
* request from multiple CPUs.
*/
- ac->ac_lg = &sbi->s_locality_groups[get_cpu()];
- put_cpu();
+ ac->ac_lg = per_cpu_ptr(sbi->s_locality_groups, smp_processor_id());
/* we're going to use group allocation */
ac->ac_flags |= EXT4_MB_HINT_GROUP_ALLOC;
--
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