Btrfs: Add a mount option to control worker thread pool size
mount -o thread_pool_size changes the default, which is
min(num_cpus + 2, 8). Larger thread pools would make more sense on
very large disk arrays.
This mount option controls the max size of each thread pool. There
are multiple thread pools, so the total worker count will be larger
than the mount option.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index f3274be..196d0e2 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -67,7 +67,7 @@
enum {
Opt_degraded, Opt_subvol, Opt_device, Opt_nodatasum, Opt_nodatacow,
Opt_max_extent, Opt_max_inline, Opt_alloc_start, Opt_nobarrier,
- Opt_ssd, Opt_err,
+ Opt_ssd, Opt_thread_pool, Opt_err,
};
static match_table_t tokens = {
@@ -80,6 +80,7 @@
{Opt_max_extent, "max_extent=%s"},
{Opt_max_inline, "max_inline=%s"},
{Opt_alloc_start, "alloc_start=%s"},
+ {Opt_thread_pool, "thread_pool=%d"},
{Opt_ssd, "ssd"},
{Opt_err, NULL}
};
@@ -118,6 +119,7 @@
struct btrfs_fs_info *info = root->fs_info;
substring_t args[MAX_OPT_ARGS];
char *p, *num;
+ int intarg;
if (!options)
return 0;
@@ -166,6 +168,15 @@
printk(KERN_INFO "btrfs: turning off barriers\n");
btrfs_set_opt(info->mount_opt, NOBARRIER);
break;
+ case Opt_thread_pool:
+ intarg = 0;
+ match_int(&args[0], &intarg);
+ if (intarg) {
+ info->thread_pool_size = intarg;
+ printk(KERN_INFO "btrfs: thread pool %d\n",
+ info->thread_pool_size);
+ }
+ break;
case Opt_max_extent:
num = match_strdup(&args[0]);
if (num) {