crush: add chooseleaf_stable tunable
Add a tunable to fix the bug that chooseleaf may cause unnecessary pg
migrations when some device fails.
Reflects ceph.git commit fdb3f664448e80d984470f32f04e2e6f03ab52ec.
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Sage Weil <sage@redhat.com>
diff --git a/include/linux/crush/crush.h b/include/linux/crush/crush.h
index 48b4930..be8f12b 100644
--- a/include/linux/crush/crush.h
+++ b/include/linux/crush/crush.h
@@ -59,7 +59,8 @@
CRUSH_RULE_SET_CHOOSELEAF_TRIES = 9, /* override chooseleaf_descend_once */
CRUSH_RULE_SET_CHOOSE_LOCAL_TRIES = 10,
CRUSH_RULE_SET_CHOOSE_LOCAL_FALLBACK_TRIES = 11,
- CRUSH_RULE_SET_CHOOSELEAF_VARY_R = 12
+ CRUSH_RULE_SET_CHOOSELEAF_VARY_R = 12,
+ CRUSH_RULE_SET_CHOOSELEAF_STABLE = 13
};
/*
@@ -205,6 +206,11 @@
* mappings line up a bit better with previous mappings. */
__u8 chooseleaf_vary_r;
+ /* if true, it makes chooseleaf firstn to return stable results (if
+ * no local retry) so that data migrations would be optimal when some
+ * device fails. */
+ __u8 chooseleaf_stable;
+
#ifndef __KERNEL__
/*
* version 0 (original) of straw_calc has various flaws. version 1