Commit 9a3b490a authored by Ilya Dryomov's avatar Ilya Dryomov
Browse files

crush: use breadth-first search for indep mode 



Reflects ceph.git commit 86e978036a4ecbac4c875e7c00f6c5bbe37282d3.

Signed-off-by: default avatarIlya Dryomov <ilya.dryomov@inktank.com>
Reviewed-by: default avatarSage Weil <sage@inktank.com>
parent c6d98a60

include/linux/crush/crush.h

+2 −1
Original line number Diff line number Diff line
@@ -22,7 +22,8 @@ 
#define CRUSH_MAX_DEPTH 10  /* max crush hierarchy depth */





#define CRUSH_ITEM_UNDEF  0x7fffffff  /* undefined result */

#define CRUSH_ITEM_UNDEF  0x7ffffffe  /* undefined result (internal use only) */

#define CRUSH_ITEM_NONE   0x7fffffff  /* no result */



/*

 * CRUSH uses user-defined "rules" to describe how inputs should be

net/ceph/crush/mapper.c

+163 −9
Original line number Diff line number Diff line
@@ -473,6 +473,148 @@ static int crush_choose(const struct crush_map *map, 
}





/**

 * choose indep: alternative breadth-first positionally stable mapping

 *

 */

static void crush_choose_indep(const struct crush_map *map,

			      struct crush_bucket *bucket,

			      const __u32 *weight, int weight_max,

			      int x, int numrep, int type,

			      int *out, int outpos,

			      int recurse_to_leaf,

			      int *out2)

{

	struct crush_bucket *in = bucket;

	int left = numrep - outpos;

	int rep;

	unsigned int ftotal;

	int r;

	int i;

	int item = 0;

	int itemtype;

	int collide;



	dprintk("CHOOSE%s INDEP bucket %d x %d outpos %d numrep %d\n", recurse_to_leaf ? "_LEAF" : "",

		bucket->id, x, outpos, numrep);



	/* initially my result is undefined */

	for (rep = outpos; rep < numrep; rep++) {

		out[rep] = CRUSH_ITEM_UNDEF;

		if (out2)

			out2[rep] = CRUSH_ITEM_UNDEF;

	}



	for (ftotal = 0; left > 0 && ftotal < map->choose_total_tries; ftotal++) {

		for (rep = outpos; rep < numrep; rep++) {

			if (out[rep] != CRUSH_ITEM_UNDEF)

				continue;



			in = bucket;  /* initial bucket */



			/* choose through intervening buckets */

			for (;;) {

				r = rep;



				/* be careful */

				if (in->alg == CRUSH_BUCKET_UNIFORM &&

				    in->size % numrep == 0)

					/* r'=r+(n+1)*f_total */

					r += (numrep+1) * ftotal;

				else

					/* r' = r + n*f_total */

					r += numrep * ftotal;



				/* bucket choose */

				if (in->size == 0) {

					dprintk("   empty bucket\n");

					break;

				}



				item = crush_bucket_choose(in, x, r);

				if (item >= map->max_devices) {

					dprintk("   bad item %d\n", item);

					out[rep] = CRUSH_ITEM_NONE;

					if (out2)

						out2[rep] = CRUSH_ITEM_NONE;

					left--;

					break;

				}



				/* desired type? */

				if (item < 0)

					itemtype = map->buckets[-1-item]->type;

				else

					itemtype = 0;

				dprintk("  item %d type %d\n", item, itemtype);



				/* keep going? */

				if (itemtype != type) {

					if (item >= 0 ||

					    (-1-item) >= map->max_buckets) {

						dprintk("   bad item type %d\n", type);

						out[rep] = CRUSH_ITEM_NONE;

						if (out2)

							out2[rep] =

								CRUSH_ITEM_NONE;

						left--;

						break;

					}

					in = map->buckets[-1-item];

					continue;

				}



				/* collision? */

				collide = 0;

				for (i = outpos; i < numrep; i++) {

					if (out[i] == item) {

						collide = 1;

						break;

					}

				}

				if (collide)

					break;



				if (recurse_to_leaf) {

					if (item < 0) {

						crush_choose_indep(map,

								   map->buckets[-1-item],

								   weight, weight_max,

								   x, rep+1, 0,

								   out2, rep,

								   0, NULL);

						if (out2[rep] == CRUSH_ITEM_NONE) {

							/* placed nothing; no leaf */

							break;

						}

					} else {

						/* we already have a leaf! */

						out2[rep] = item;

					}

				}



				/* out? */

				if (itemtype == 0 &&

				    is_out(map, weight, weight_max, item, x))

					break;



				/* yay! */

				out[rep] = item;

				left--;

				break;

			}

		}

	}

	for (rep = outpos; rep < numrep; rep++) {

		if (out[rep] == CRUSH_ITEM_UNDEF) {

			out[rep] = CRUSH_ITEM_NONE;

		}

		if (out2 && out2[rep] == CRUSH_ITEM_UNDEF) {

			out2[rep] = CRUSH_ITEM_NONE;

		}

	}

}



/**

 * crush_do_rule - calculate a mapping with the given input and rule

 * @map: the crush_map
@@ -556,6 +698,7 @@ int crush_do_rule(const struct crush_map *map, 
						continue;

				}

				j = 0;

				if (firstn) {

					osize += crush_choose(map,

							      map->buckets[-1-w[i]],

							      weight, weight_max,
@@ -565,6 +708,17 @@ int crush_do_rule(const struct crush_map *map, 
							      firstn,

							      recurse_to_leaf,

							      descend_once, c+osize);

				} else {

					crush_choose_indep(map,

							   map->buckets[-1-w[i]],

							   weight, weight_max,

							   x, numrep,

							   curstep->arg2,

							   o+osize, j,

							   recurse_to_leaf,

							   c+osize);

					osize += numrep;

				}

			}



			if (recurse_to_leaf)