Reduce ioprio class of scrub readahead threads to idle priority.
This setting is fixed. This priority has shown the best performance
during all measurements.
Signed-off-by: Stefan Behrens <sbehr...@giantdisaster.de>
---
fs/btrfs/ctree.h | 3 +++
fs/btrfs/reada.c | 5 +++++
2 files changed, 8 insertions(+)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index ec42a24..e6f772d 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -173,6 +173,9 @@ static int btrfs_csum_sizes[] = { 4, 0 };
#define BTRFS_FT_XATTR 8
#define BTRFS_FT_MAX 9
+/* ioprio of readahead is set to idle */
+#define BTRFS_IOPRIO_READA (IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0))
+
/*
* The key defines the order in the tree, and so it also defines (optimal)
* block layout.
diff --git a/fs/btrfs/reada.c b/fs/btrfs/reada.c
index ac5d010..48a4882 100644
--- a/fs/btrfs/reada.c
+++ b/fs/btrfs/reada.c
@@ -718,13 +718,18 @@ static void reada_start_machine_worker(struct btrfs_work
*work)
{
struct reada_machine_work *rmw;
struct btrfs_fs_info *fs_info;
+ int old_ioprio;
rmw = container_of(work, struct reada_machine_work, work);
fs_info = rmw->fs_info;
kfree(rmw);
+ old_ioprio = IOPRIO_PRIO_VALUE(task_nice_ioclass(current),
+ task_nice_ioprio(current));
+ set_task_ioprio(current, BTRFS_IOPRIO_READA);
__reada_start_machine(fs_info);
+ set_task_ioprio(current, old_ioprio);
}
static void __reada_start_machine(struct btrfs_fs_info *fs_info)
--
1.7.10.2
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