linux/crush/crush.h

1 /* SPDX-License-Identifier: GPL-2.0 */
13  * CRUSH is a pseudo-random data distribution algorithm that
20  *     https://www.ssrc.ucsc.edu/Papers/weil-sc06.pdf
39  * CRUSH uses user-defined "rules" to describe how inputs should be
53 	CRUSH_RULE_CHOOSE_FIRSTN = 2, /* arg1 = num items to pick */
69  * for specifying choose num (arg1) relative to the max parameter
73 #define CRUSH_CHOOSE_N_MINUS(x)   (-(x))
106  *  ------------------------------------------------
133 	__u16 type;      /* non-zero; type=0 is reserved for devices */
136 	__u32 weight;    /* 16-bit fixed point */
137 	__u32 size;      /* num items */
157  * Replacement weights and ids for a given straw2 bucket, for
163  * __weight_set_size__, the weights found at __weight_set_size-1__ are
176 	__s32 *ids;            /*!< values to use instead of items */  member
185  * Replacement weights and ids for each bucket in the crushmap. The
187  * __map->max_buckets__.
190  * an item from the bucket __map->buckets[N]__ bucket, provided it
206 	__u32 item_weight;  /* 16-bit fixed point; all items equally weighted */
211 	__u32 *item_weights;  /* 16-bit fixed point */
212 	__u32 *sum_weights;   /* 16-bit fixed point.  element i is sum
225 	__u32 *item_weights;   /* 16-bit fixed point */
226 	__u32 *straws;         /* 16-bit fixed point */
231 	__u32 *item_weights;   /* 16-bit fixed point */
247 	/* choose local retries before re-descent */
250 	 * re-descent */
260 	/* if non-zero, feed r into chooseleaf, bit-shifted right by (r-1)
304 	/* device/bucket type id -> type name (CrushWrapper::type_map) */
307 	/* device/bucket id -> name (CrushWrapper::name_map) */
329 	return ((i+1) << 1)-1;  in crush_calc_tree_node()
343 	__u32 perm_n; /* num elements of *perm that are permuted/defined */
348 	struct crush_work_bucket **work; /* Per-bucket working store */