@@ -59,7 +59,8 @@ enum {
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 @@ struct crush_map {
* 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
@@ -403,6 +403,7 @@ static int is_out(const struct crush_map *map,
* @local_retries: localized retries
* @local_fallback_retries: localized fallback retries
* @recurse_to_leaf: true if we want one device under each item of given type (chooseleaf instead of choose)
+ * @stable: stable mode starts rep=0 in the recursive call for all replicas
* @vary_r: pass r to recursive calls
* @out2: second output vector for leaf items (if @recurse_to_leaf)
* @parent_r: r value passed from the parent
@@ -419,6 +420,7 @@ static int crush_choose_firstn(const struct crush_map *map,
unsigned int local_fallback_retries,
int recurse_to_leaf,
unsigned int vary_r,
+ unsigned int stable,
int *out2,
int parent_r)
{
@@ -433,13 +435,13 @@ static int crush_choose_firstn(const struct crush_map *map,
int collide, reject;
int count = out_size;
- dprintk("CHOOSE%s bucket %d x %d outpos %d numrep %d tries %d recurse_tries %d local_retries %d local_fallback_retries %d parent_r %d\n",
+ dprintk("CHOOSE%s bucket %d x %d outpos %d numrep %d tries %d recurse_tries %d local_retries %d local_fallback_retries %d parent_r %d stable %d\n",
recurse_to_leaf ? "_LEAF" : "",
bucket->id, x, outpos, numrep,
tries, recurse_tries, local_retries, local_fallback_retries,
- parent_r);
+ parent_r, stable);
- for (rep = outpos; rep < numrep && count > 0 ; rep++) {
+ for (rep = stable ? 0 : outpos; rep < numrep && count > 0 ; rep++) {
/* keep trying until we get a non-out, non-colliding item */
ftotal = 0;
skip_rep = 0;
@@ -512,13 +514,14 @@ static int crush_choose_firstn(const struct crush_map *map,
if (crush_choose_firstn(map,
map->buckets[-1-item],
weight, weight_max,
- x, outpos+1, 0,
+ x, stable ? 1 : outpos+1, 0,
out2, outpos, count,
recurse_tries, 0,
local_retries,
local_fallback_retries,
0,
vary_r,
+ stable,
NULL,
sub_r) <= outpos)
/* didn't get leaf */
@@ -816,6 +819,7 @@ int crush_do_rule(const struct crush_map *map,
int choose_local_fallback_retries = map->choose_local_fallback_tries;
int vary_r = map->chooseleaf_vary_r;
+ int stable = map->chooseleaf_stable;
if ((__u32)ruleno >= map->max_rules) {
dprintk(" bad ruleno %d\n", ruleno);
@@ -870,6 +874,11 @@ int crush_do_rule(const struct crush_map *map,
vary_r = curstep->arg1;
break;
+ case CRUSH_RULE_SET_CHOOSELEAF_STABLE:
+ if (curstep->arg1 >= 0)
+ stable = curstep->arg1;
+ break;
+
case CRUSH_RULE_CHOOSELEAF_FIRSTN:
case CRUSH_RULE_CHOOSE_FIRSTN:
firstn = 1;
@@ -932,6 +941,7 @@ int crush_do_rule(const struct crush_map *map,
choose_local_fallback_retries,
recurse_to_leaf,
vary_r,
+ stable,
c+osize,
0);
} else {
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> --- include/linux/crush/crush.h | 8 +++++++- net/ceph/crush/mapper.c | 18 ++++++++++++++---- 2 files changed, 21 insertions(+), 5 deletions(-)