On Mon, 3 Feb 2014, Ilya Dryomov wrote:
> With the addition of erasure coding support in the future, scratch
> variable-length array in crush_do_rule_ary() is going to grow to at
> least 200 bytes on average, on top of another 128 bytes consumed by
> rawosd/osd arrays in the call chain. Replace it with a buffer inside
> struct osdmap and a mutex. This shouldn't result in any contention,
> because all osd requests were already serialized by request_mutex at
> that point; the only unlocked caller was ceph_ioctl_get_dataloc().
>
> Signed-off-by: Ilya Dryomov <[email protected]>
> ---
> include/linux/ceph/osdmap.h | 3 +++
> net/ceph/osdmap.c | 25 ++++++++++++++++---------
> 2 files changed, 19 insertions(+), 9 deletions(-)
>
> diff --git a/include/linux/ceph/osdmap.h b/include/linux/ceph/osdmap.h
> index 49ff69f0746b..8c8b3cefc28b 100644
> --- a/include/linux/ceph/osdmap.h
> +++ b/include/linux/ceph/osdmap.h
> @@ -84,6 +84,9 @@ struct ceph_osdmap {
> /* the CRUSH map specifies the mapping of placement groups to
> * the list of osds that store+replicate them. */
> struct crush_map *crush;
> +
> + struct mutex crush_scratch_mutex;
> + int crush_scratch_ary[CEPH_PG_MAX_SIZE * 3];
There are no users for CEPH_PG_MAX_SIZE (16) in the userland code. I
would stick in a BUG_ON or WARN_ON just to make sure we don't get an
OSDMap with more OSDs than that.
> };
>
> static inline void ceph_oid_set_name(struct ceph_object_id *oid,
> diff --git a/net/ceph/osdmap.c b/net/ceph/osdmap.c
> index aade4a5c1c07..9d1aaa24def6 100644
> --- a/net/ceph/osdmap.c
> +++ b/net/ceph/osdmap.c
> @@ -698,7 +698,9 @@ struct ceph_osdmap *osdmap_decode(void **p, void *end)
> map = kzalloc(sizeof(*map), GFP_NOFS);
> if (map == NULL)
> return ERR_PTR(-ENOMEM);
> +
> map->pg_temp = RB_ROOT;
> + mutex_init(&map->crush_scratch_mutex);
>
> ceph_decode_16_safe(p, end, version, bad);
> if (version > 6) {
> @@ -1142,14 +1144,20 @@ int ceph_oloc_oid_to_pg(struct ceph_osdmap *osdmap,
> }
> EXPORT_SYMBOL(ceph_oloc_oid_to_pg);
>
> -static int crush_do_rule_ary(const struct crush_map *map, int ruleno, int x,
> - int *result, int result_max,
> - const __u32 *weight, int weight_max)
> +static int do_crush(struct ceph_osdmap *map, int ruleno, int x,
> + int *result, int result_max,
> + const __u32 *weight, int weight_max)
> {
> - int scratch[result_max * 3];
> + int r;
> +
> + BUG_ON(result_max > CEPH_PG_MAX_SIZE);
> +
> + mutex_lock(&map->crush_scratch_mutex);
> + r = crush_do_rule(map->crush, ruleno, x, result, result_max,
> + weight, weight_max, map->crush_scratch_ary);
> + mutex_unlock(&map->crush_scratch_mutex);
>
> - return crush_do_rule(map, ruleno, x, result, result_max,
> - weight, weight_max, scratch);
> + return r;
> }
>
> /*
> @@ -1205,9 +1213,8 @@ static int *calc_pg_raw(struct ceph_osdmap *osdmap,
> struct ceph_pg pgid,
> pool->pgp_num_mask) +
> (unsigned)pgid.pool;
> }
> - r = crush_do_rule_ary(osdmap->crush, ruleno, pps,
> - osds, min_t(int, pool->size, *num),
> - osdmap->osd_weight, osdmap->max_osd);
> + r = do_crush(osdmap, ruleno, pps, osds, min_t(int, pool->size, *num),
> + osdmap->osd_weight, osdmap->max_osd);
> if (r < 0) {
> pr_err("error %d from crush rule: pool %lld ruleset %d type %d"
> " size %d\n", r, pgid.pool, pool->crush_ruleset,
> --
> 1.7.10.4
>
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