Btrfs: Allow worker threads to exit when idle
The Btrfs worker threads don't currently die off after they have
been idle for a while, leading to a lot of threads sitting around
doing nothing for each mount.
Also, they are unable to start atomically (from end_io hanlders).
This commit reworks the worker threads so they can be started
from end_io handlers (just setting a flag that asks for a thread
to be added at a later date) and so they can exit if they
have been idle for a long time.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 3cf4cfa..20cefc6 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1682,7 +1682,7 @@
err = -EINVAL;
goto fail_iput;
}
-
+printk("thread pool is %d\n", fs_info->thread_pool_size);
/*
* we need to start all the end_io workers up front because the
* queue work function gets called at interrupt time, and so it
@@ -1727,20 +1727,22 @@
fs_info->endio_workers.idle_thresh = 4;
fs_info->endio_meta_workers.idle_thresh = 4;
- fs_info->endio_write_workers.idle_thresh = 64;
- fs_info->endio_meta_write_workers.idle_thresh = 64;
+ fs_info->endio_write_workers.idle_thresh = 2;
+ fs_info->endio_meta_write_workers.idle_thresh = 2;
+
+ fs_info->endio_workers.atomic_worker_start = 1;
+ fs_info->endio_meta_workers.atomic_worker_start = 1;
+ fs_info->endio_write_workers.atomic_worker_start = 1;
+ fs_info->endio_meta_write_workers.atomic_worker_start = 1;
btrfs_start_workers(&fs_info->workers, 1);
btrfs_start_workers(&fs_info->submit_workers, 1);
btrfs_start_workers(&fs_info->delalloc_workers, 1);
btrfs_start_workers(&fs_info->fixup_workers, 1);
- btrfs_start_workers(&fs_info->endio_workers, fs_info->thread_pool_size);
- btrfs_start_workers(&fs_info->endio_meta_workers,
- fs_info->thread_pool_size);
- btrfs_start_workers(&fs_info->endio_meta_write_workers,
- fs_info->thread_pool_size);
- btrfs_start_workers(&fs_info->endio_write_workers,
- fs_info->thread_pool_size);
+ btrfs_start_workers(&fs_info->endio_workers, 1);
+ btrfs_start_workers(&fs_info->endio_meta_workers, 1);
+ btrfs_start_workers(&fs_info->endio_meta_write_workers, 1);
+ btrfs_start_workers(&fs_info->endio_write_workers, 1);
fs_info->bdi.ra_pages *= btrfs_super_num_devices(disk_super);
fs_info->bdi.ra_pages = max(fs_info->bdi.ra_pages,