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crush: apply chooseleaf_tries to firstn mode too

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Parameterize the attempts for the _firstn choose method, and apply the
rule-specified tries count to firstn mode as well.  Note that we have
slightly different behavior here than with indep:

 If the firstn value is not specified for firstn, we pass through the
 normal attempt count.  This maintains compatibility with legacy behavior.
 Note that this is usually *not* actually N^2 work, though, because of the
 descend_once tunable.  However, descend_once is unfortunately *not* the
 same thing as 1 chooseleaf try because it is only checked on a reject but
 not on a collision.  Sigh.

 In contrast, for indep, if tries is not specified we default to 1
 recursive attempt, because that is simply more sane, and we have the
 option to do so.  The descend_once tunable has no effect for indep.

Reflects ceph.git commit 64aeded50d80942d66a5ec7b604ff2fcbf5d7b63.

Signed-off-by: Ilya Dryomov <ilya.dryomov@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
This commit is contained in:
Ilya Dryomov 2013-12-24 21:19:26 +02:00
parent be3226acc5
commit f18650ace3
2 changed files with 14 additions and 5 deletions
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5
include/linux/crush/crush.h
View file

@ -165,7 +165,10 @@ struct crush_map {
__u32 choose_local_fallback_tries;
/* choose attempts before giving up */
__u32 choose_total_tries;
/* attempt chooseleaf inner descent once; on failure retry outer descent */
/* attempt chooseleaf inner descent once for firstn mode; on
* reject retry outer descent. Note that this does *not*
* apply to a collision: in that case we will retry as we used
* to. */
__u32 chooseleaf_descend_once;
};

14
net/ceph/crush/mapper.c
View file

@ -299,6 +299,8 @@ static int crush_choose_firstn(const struct crush_map *map,
const __u32 *weight, int weight_max,
int x, int numrep, int type,
int *out, int outpos,
unsigned int attempts,
unsigned int recurse_attempts,
int recurse_to_leaf,
int descend_once, int *out2)
{
@ -385,6 +387,7 @@ static int crush_choose_firstn(const struct crush_map *map,
weight, weight_max,
x, outpos+1, 0,
out2, outpos,
recurse_attempts, 0,
0,
map->chooseleaf_descend_once,
NULL) <= outpos)
@ -421,7 +424,7 @@ static int crush_choose_firstn(const struct crush_map *map,
flocal <= in->size + map->choose_local_fallback_tries)
/* exhaustive bucket search */
retry_bucket = 1;
else if (ftotal <= map->choose_total_tries)
else if (ftotal <= attempts)
/* then retry descent */
retry_descent = 1;
else
@ -634,7 +637,8 @@ int crush_do_rule(const struct crush_map *map,
__u32 step;
int i, j;
int numrep;
int choose_leaf_tries = 1;
int choose_tries = map->choose_total_tries;
int choose_leaf_tries = 0;
const int descend_once = 0;
if ((__u32)ruleno >= map->max_rules) {
@ -701,6 +705,8 @@ int crush_do_rule(const struct crush_map *map,
x, numrep,
curstep->arg2,
o+osize, j,
choose_tries,
choose_leaf_tries ? choose_leaf_tries : choose_tries,
recurse_to_leaf,
descend_once, c+osize);
} else {
@ -711,8 +717,8 @@ int crush_do_rule(const struct crush_map *map,
x, numrep, numrep,
curstep->arg2,
o+osize, j,
map->choose_total_tries,
choose_leaf_tries,
choose_tries,
choose_leaf_tries ? choose_leaf_tries : 1,
recurse_to_leaf,
c+osize,
0);