From d223a57954b158084e9be1ab9580ea50fea4fa66 Mon Sep 17 00:00:00 2001 From: Ilya Dryomov Date: Sun, 31 Jan 2016 14:36:07 +0100 Subject: [PATCH] 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 --- include/linux/crush/crush.h | 8 +++++++- net/ceph/crush/mapper.c | 18 ++++++++++++++---- 2 files changed, 21 insertions(+), 5 deletions(-) diff --git a/include/linux/crush/crush.h b/include/linux/crush/crush.h index 48b49305716b..be8f12b8f195 100644 --- a/include/linux/crush/crush.h +++ b/include/linux/crush/crush.h @@ -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 diff --git a/net/ceph/crush/mapper.c b/net/ceph/crush/mapper.c index abb700621e4a..5fcfb98f309e 100644 --- a/net/ceph/crush/mapper.c +++ b/net/ceph/crush/mapper.c @@ -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 { -- 2.39.5