On 04/10/2017 04:11 PM, Sage Weil wrote:
> On Mon, 10 Apr 2017, Loic Dachary wrote:
>> Hi Sage,
>>
>> We could have:
>>
>> struct crush_choose_arg {
>> __u32 bucket_id;
>> __u32 num_items;
>> __u32 *ids; // override the bucket items for placement
>> __u32 num_positions;
>> __u32 *weights; // size is num_positions*num_items
>> };
>>
>> struct crush_choose_arg_map {
>> struct crush_choose_arg *args;
>> __u32 size;
>> };
>>
>> and
>>
>> void crush_init_workspace(const struct crush_map *m, struct crush_choose_arg_map *arg_map, void *v) {
>> ...
>> if (m->buckets[b]->id == arg_map[b]->bucket_id)
>> w->work[b]->arg = arg_map[b];
>> ...
>> }
>>
>> with
>>
>> struct crush_work_bucket {
>> __u32 perm_x; /* @x for which *perm is defined */
>> __u32 perm_n; /* num elements of *perm that are permuted/defined */
>> __u32 *perm; /* Permutation of the bucket's items */
>> struct crush_choose_arg *arg;
>> };
>>
>> There would be no need to change the code path since crush_bucket_choose
>> already is given the crush_work_bucket. And crush_init_workspace already
>> has logic that is algorithm dependent. And all the sanity checks could
>> be done in crush_init_workspace so that the choose function only does
>> what's absolutely necessary.
>
> Allowing overrides of the bucket items too makes me nervous (do we have a
> use for that yet?),
Maybe I misunderstood what you were after with bucket_id in http://pad.ceph.com/p/crush-multiweight around here ?
struct crush_bucket_weight_set {
__u32 bucket_id; /* used as input to hash in place of bucket id */
__u32 num_positions, num_items;
__u32 *data; // index like [item*num_items+pos]
};
> but otherwise this looks reasonable!
Cool :-)
--
Loïc Dachary, Artisan Logiciel Libre
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