diff options
Diffstat (limited to 'net/ceph/crush/mapper.c')
| -rw-r--r-- | net/ceph/crush/mapper.c | 927 |
1 files changed, 927 insertions, 0 deletions
diff --git a/net/ceph/crush/mapper.c b/net/ceph/crush/mapper.c new file mode 100644 index 000000000..5b47736d2 --- /dev/null +++ b/net/ceph/crush/mapper.c @@ -0,0 +1,927 @@ + +#ifdef __KERNEL__ +# include <linux/string.h> +# include <linux/slab.h> +# include <linux/bug.h> +# include <linux/kernel.h> +# ifndef dprintk +# define dprintk(args...) +# endif +#else +# include <string.h> +# include <stdio.h> +# include <stdlib.h> +# include <assert.h> +# define BUG_ON(x) assert(!(x)) +# define dprintk(args...) /* printf(args) */ +# define kmalloc(x, f) malloc(x) +# define kfree(x) free(x) +#endif + +#include <linux/crush/crush.h> +#include <linux/crush/hash.h> +#include "crush_ln_table.h" + +/* + * Implement the core CRUSH mapping algorithm. + */ + +/** + * crush_find_rule - find a crush_rule id for a given ruleset, type, and size. + * @map: the crush_map + * @ruleset: the storage ruleset id (user defined) + * @type: storage ruleset type (user defined) + * @size: output set size + */ +int crush_find_rule(const struct crush_map *map, int ruleset, int type, int size) +{ + __u32 i; + + for (i = 0; i < map->max_rules; i++) { + if (map->rules[i] && + map->rules[i]->mask.ruleset == ruleset && + map->rules[i]->mask.type == type && + map->rules[i]->mask.min_size <= size && + map->rules[i]->mask.max_size >= size) + return i; + } + return -1; +} + + +/* + * bucket choose methods + * + * For each bucket algorithm, we have a "choose" method that, given a + * crush input @x and replica position (usually, position in output set) @r, + * will produce an item in the bucket. + */ + +/* + * Choose based on a random permutation of the bucket. + * + * We used to use some prime number arithmetic to do this, but it + * wasn't very random, and had some other bad behaviors. Instead, we + * calculate an actual random permutation of the bucket members. + * Since this is expensive, we optimize for the r=0 case, which + * captures the vast majority of calls. + */ +static int bucket_perm_choose(struct crush_bucket *bucket, + int x, int r) +{ + unsigned int pr = r % bucket->size; + unsigned int i, s; + + /* start a new permutation if @x has changed */ + if (bucket->perm_x != (__u32)x || bucket->perm_n == 0) { + dprintk("bucket %d new x=%d\n", bucket->id, x); + bucket->perm_x = x; + + /* optimize common r=0 case */ + if (pr == 0) { + s = crush_hash32_3(bucket->hash, x, bucket->id, 0) % + bucket->size; + bucket->perm[0] = s; + bucket->perm_n = 0xffff; /* magic value, see below */ + goto out; + } + + for (i = 0; i < bucket->size; i++) + bucket->perm[i] = i; + bucket->perm_n = 0; + } else if (bucket->perm_n == 0xffff) { + /* clean up after the r=0 case above */ + for (i = 1; i < bucket->size; i++) + bucket->perm[i] = i; + bucket->perm[bucket->perm[0]] = 0; + bucket->perm_n = 1; + } + + /* calculate permutation up to pr */ + for (i = 0; i < bucket->perm_n; i++) + dprintk(" perm_choose have %d: %d\n", i, bucket->perm[i]); + while (bucket->perm_n <= pr) { + unsigned int p = bucket->perm_n; + /* no point in swapping the final entry */ + if (p < bucket->size - 1) { + i = crush_hash32_3(bucket->hash, x, bucket->id, p) % + (bucket->size - p); + if (i) { + unsigned int t = bucket->perm[p + i]; + bucket->perm[p + i] = bucket->perm[p]; + bucket->perm[p] = t; + } + dprintk(" perm_choose swap %d with %d\n", p, p+i); + } + bucket->perm_n++; + } + for (i = 0; i < bucket->size; i++) + dprintk(" perm_choose %d: %d\n", i, bucket->perm[i]); + + s = bucket->perm[pr]; +out: + dprintk(" perm_choose %d sz=%d x=%d r=%d (%d) s=%d\n", bucket->id, + bucket->size, x, r, pr, s); + return bucket->items[s]; +} + +/* uniform */ +static int bucket_uniform_choose(struct crush_bucket_uniform *bucket, + int x, int r) +{ + return bucket_perm_choose(&bucket->h, x, r); +} + +/* list */ +static int bucket_list_choose(struct crush_bucket_list *bucket, + int x, int r) +{ + int i; + + for (i = bucket->h.size-1; i >= 0; i--) { + __u64 w = crush_hash32_4(bucket->h.hash,x, bucket->h.items[i], + r, bucket->h.id); + w &= 0xffff; + dprintk("list_choose i=%d x=%d r=%d item %d weight %x " + "sw %x rand %llx", + i, x, r, bucket->h.items[i], bucket->item_weights[i], + bucket->sum_weights[i], w); + w *= bucket->sum_weights[i]; + w = w >> 16; + /*dprintk(" scaled %llx\n", w);*/ + if (w < bucket->item_weights[i]) + return bucket->h.items[i]; + } + + dprintk("bad list sums for bucket %d\n", bucket->h.id); + return bucket->h.items[0]; +} + + +/* (binary) tree */ +static int height(int n) +{ + int h = 0; + while ((n & 1) == 0) { + h++; + n = n >> 1; + } + return h; +} + +static int left(int x) +{ + int h = height(x); + return x - (1 << (h-1)); +} + +static int right(int x) +{ + int h = height(x); + return x + (1 << (h-1)); +} + +static int terminal(int x) +{ + return x & 1; +} + +static int bucket_tree_choose(struct crush_bucket_tree *bucket, + int x, int r) +{ + int n; + __u32 w; + __u64 t; + + /* start at root */ + n = bucket->num_nodes >> 1; + + while (!terminal(n)) { + int l; + /* pick point in [0, w) */ + w = bucket->node_weights[n]; + t = (__u64)crush_hash32_4(bucket->h.hash, x, n, r, + bucket->h.id) * (__u64)w; + t = t >> 32; + + /* descend to the left or right? */ + l = left(n); + if (t < bucket->node_weights[l]) + n = l; + else + n = right(n); + } + + return bucket->h.items[n >> 1]; +} + + +/* straw */ + +static int bucket_straw_choose(struct crush_bucket_straw *bucket, + int x, int r) +{ + __u32 i; + int high = 0; + __u64 high_draw = 0; + __u64 draw; + + for (i = 0; i < bucket->h.size; i++) { + draw = crush_hash32_3(bucket->h.hash, x, bucket->h.items[i], r); + draw &= 0xffff; + draw *= bucket->straws[i]; + if (i == 0 || draw > high_draw) { + high = i; + high_draw = draw; + } + } + return bucket->h.items[high]; +} + +// compute 2^44*log2(input+1) +uint64_t crush_ln(unsigned xin) +{ + unsigned x=xin, x1; + int iexpon, index1, index2; + uint64_t RH, LH, LL, xl64, result; + + x++; + + // normalize input + iexpon = 15; + while(!(x&0x18000)) { x<<=1; iexpon--; } + + index1 = (x>>8)<<1; + // RH ~ 2^56/index1 + RH = __RH_LH_tbl[index1 - 256]; + // LH ~ 2^48 * log2(index1/256) + LH = __RH_LH_tbl[index1 + 1 - 256]; + + // RH*x ~ 2^48 * (2^15 + xf), xf<2^8 + xl64 = (int64_t)x * RH; + xl64 >>= 48; + x1 = xl64; + + result = iexpon; + result <<= (12 + 32); + + index2 = x1 & 0xff; + // LL ~ 2^48*log2(1.0+index2/2^15) + LL = __LL_tbl[index2]; + + LH = LH + LL; + + LH >>= (48-12 - 32); + result += LH; + + return result; +} + + +/* + * straw2 + * + * for reference, see: + * + * http://en.wikipedia.org/wiki/Exponential_distribution#Distribution_of_the_minimum_of_exponential_random_variables + * + */ + +static int bucket_straw2_choose(struct crush_bucket_straw2 *bucket, + int x, int r) +{ + unsigned i, high = 0; + unsigned u; + unsigned w; + __s64 ln, draw, high_draw = 0; + + for (i = 0; i < bucket->h.size; i++) { + w = bucket->item_weights[i]; + if (w) { + u = crush_hash32_3(bucket->h.hash, x, + bucket->h.items[i], r); + u &= 0xffff; + + /* + * for some reason slightly less than 0x10000 produces + * a slightly more accurate distribution... probably a + * rounding effect. + * + * the natural log lookup table maps [0,0xffff] + * (corresponding to real numbers [1/0x10000, 1] to + * [0, 0xffffffffffff] (corresponding to real numbers + * [-11.090355,0]). + */ + ln = crush_ln(u) - 0x1000000000000ll; + + /* + * divide by 16.16 fixed-point weight. note + * that the ln value is negative, so a larger + * weight means a larger (less negative) value + * for draw. + */ + draw = div64_s64(ln, w); + } else { + draw = S64_MIN; + } + + if (i == 0 || draw > high_draw) { + high = i; + high_draw = draw; + } + } + return bucket->h.items[high]; +} + + +static int crush_bucket_choose(struct crush_bucket *in, int x, int r) +{ + dprintk(" crush_bucket_choose %d x=%d r=%d\n", in->id, x, r); + BUG_ON(in->size == 0); + switch (in->alg) { + case CRUSH_BUCKET_UNIFORM: + return bucket_uniform_choose((struct crush_bucket_uniform *)in, + x, r); + case CRUSH_BUCKET_LIST: + return bucket_list_choose((struct crush_bucket_list *)in, + x, r); + case CRUSH_BUCKET_TREE: + return bucket_tree_choose((struct crush_bucket_tree *)in, + x, r); + case CRUSH_BUCKET_STRAW: + return bucket_straw_choose((struct crush_bucket_straw *)in, + x, r); + case CRUSH_BUCKET_STRAW2: + return bucket_straw2_choose((struct crush_bucket_straw2 *)in, + x, r); + default: + dprintk("unknown bucket %d alg %d\n", in->id, in->alg); + return in->items[0]; + } +} + + +/* + * true if device is marked "out" (failed, fully offloaded) + * of the cluster + */ +static int is_out(const struct crush_map *map, + const __u32 *weight, int weight_max, + int item, int x) +{ + if (item >= weight_max) + return 1; + if (weight[item] >= 0x10000) + return 0; + if (weight[item] == 0) + return 1; + if ((crush_hash32_2(CRUSH_HASH_RJENKINS1, x, item) & 0xffff) + < weight[item]) + return 0; + return 1; +} + +/** + * crush_choose_firstn - choose numrep distinct items of given type + * @map: the crush_map + * @bucket: the bucket we are choose an item from + * @x: crush input value + * @numrep: the number of items to choose + * @type: the type of item to choose + * @out: pointer to output vector + * @outpos: our position in that vector + * @out_size: size of the out vector + * @tries: number of attempts to make + * @recurse_tries: number of attempts to have recursive chooseleaf make + * @local_retries: localized retries + * @local_fallback_retries: localized fallback retries + * @recurse_to_leaf: true if we want one device under each item of given type (chooseleaf instead of choose) + * @vary_r: pass r to recursive calls + * @out2: second output vector for leaf items (if @recurse_to_leaf) + * @parent_r: r value passed from the parent + */ +static int crush_choose_firstn(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 out_size, + unsigned int tries, + unsigned int recurse_tries, + unsigned int local_retries, + unsigned int local_fallback_retries, + int recurse_to_leaf, + unsigned int vary_r, + int *out2, + int parent_r) +{ + int rep; + unsigned int ftotal, flocal; + int retry_descent, retry_bucket, skip_rep; + struct crush_bucket *in = bucket; + int r; + int i; + int item = 0; + int itemtype; + int collide, reject; + int count = out_size; + + dprintk("CHOOSE%s bucket %d x %d outpos %d numrep %d tries %d recurse_tries %d local_retries %d local_fallback_retries %d parent_r %d\n", + recurse_to_leaf ? "_LEAF" : "", + bucket->id, x, outpos, numrep, + tries, recurse_tries, local_retries, local_fallback_retries, + parent_r); + + for (rep = outpos; rep < numrep && count > 0 ; rep++) { + /* keep trying until we get a non-out, non-colliding item */ + ftotal = 0; + skip_rep = 0; + do { + retry_descent = 0; + in = bucket; /* initial bucket */ + + /* choose through intervening buckets */ + flocal = 0; + do { + collide = 0; + retry_bucket = 0; + r = rep + parent_r; + /* r' = r + f_total */ + r += ftotal; + + /* bucket choose */ + if (in->size == 0) { + reject = 1; + goto reject; + } + if (local_fallback_retries > 0 && + flocal >= (in->size>>1) && + flocal > local_fallback_retries) + item = bucket_perm_choose(in, x, r); + else + item = crush_bucket_choose(in, x, r); + if (item >= map->max_devices) { + dprintk(" bad item %d\n", item); + skip_rep = 1; + 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); + skip_rep = 1; + break; + } + in = map->buckets[-1-item]; + retry_bucket = 1; + continue; + } + + /* collision? */ + for (i = 0; i < outpos; i++) { + if (out[i] == item) { + collide = 1; + break; + } + } + + reject = 0; + if (!collide && recurse_to_leaf) { + if (item < 0) { + int sub_r; + if (vary_r) + sub_r = r >> (vary_r-1); + else + sub_r = 0; + if (crush_choose_firstn(map, + map->buckets[-1-item], + weight, weight_max, + x, outpos+1, 0, + out2, outpos, count, + recurse_tries, 0, + local_retries, + local_fallback_retries, + 0, + vary_r, + NULL, + sub_r) <= outpos) + /* didn't get leaf */ + reject = 1; + } else { + /* we already have a leaf! */ + out2[outpos] = item; + } + } + + if (!reject) { + /* out? */ + if (itemtype == 0) + reject = is_out(map, weight, + weight_max, + item, x); + else + reject = 0; + } + +reject: + if (reject || collide) { + ftotal++; + flocal++; + + if (collide && flocal <= local_retries) + /* retry locally a few times */ + retry_bucket = 1; + else if (local_fallback_retries > 0 && + flocal <= in->size + local_fallback_retries) + /* exhaustive bucket search */ + retry_bucket = 1; + else if (ftotal < tries) + /* then retry descent */ + retry_descent = 1; + else + /* else give up */ + skip_rep = 1; + dprintk(" reject %d collide %d " + "ftotal %u flocal %u\n", + reject, collide, ftotal, + flocal); + } + } while (retry_bucket); + } while (retry_descent); + + if (skip_rep) { + dprintk("skip rep\n"); + continue; + } + + dprintk("CHOOSE got %d\n", item); + out[outpos] = item; + outpos++; + count--; + } + + dprintk("CHOOSE returns %d\n", outpos); + return outpos; +} + + +/** + * crush_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 left, int numrep, int type, + int *out, int outpos, + unsigned int tries, + unsigned int recurse_tries, + int recurse_to_leaf, + int *out2, + int parent_r) +{ + struct crush_bucket *in = bucket; + int endpos = outpos + left; + 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 < endpos; rep++) { + out[rep] = CRUSH_ITEM_UNDEF; + if (out2) + out2[rep] = CRUSH_ITEM_UNDEF; + } + + for (ftotal = 0; left > 0 && ftotal < tries; ftotal++) { + for (rep = outpos; rep < endpos; rep++) { + if (out[rep] != CRUSH_ITEM_UNDEF) + continue; + + in = bucket; /* initial bucket */ + + /* choose through intervening buckets */ + for (;;) { + /* note: we base the choice on the position + * even in the nested call. that means that + * if the first layer chooses the same bucket + * in a different position, we will tend to + * choose a different item in that bucket. + * this will involve more devices in data + * movement and tend to distribute the load. + */ + r = rep + parent_r; + + /* 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 < endpos; 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, 1, numrep, 0, + out2, rep, + recurse_tries, 0, + 0, NULL, r); + 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 < endpos; 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 + * @ruleno: the rule id + * @x: hash input + * @result: pointer to result vector + * @result_max: maximum result size + * @weight: weight vector (for map leaves) + * @weight_max: size of weight vector + * @scratch: scratch vector for private use; must be >= 3 * result_max + */ +int crush_do_rule(const struct crush_map *map, + int ruleno, int x, int *result, int result_max, + const __u32 *weight, int weight_max, + int *scratch) +{ + int result_len; + int *a = scratch; + int *b = scratch + result_max; + int *c = scratch + result_max*2; + int recurse_to_leaf; + int *w; + int wsize = 0; + int *o; + int osize; + int *tmp; + struct crush_rule *rule; + __u32 step; + int i, j; + int numrep; + int out_size; + /* + * the original choose_total_tries value was off by one (it + * counted "retries" and not "tries"). add one. + */ + int choose_tries = map->choose_total_tries + 1; + int choose_leaf_tries = 0; + /* + * the local tries values were counted as "retries", though, + * and need no adjustment + */ + int choose_local_retries = map->choose_local_tries; + int choose_local_fallback_retries = map->choose_local_fallback_tries; + + int vary_r = map->chooseleaf_vary_r; + + if ((__u32)ruleno >= map->max_rules) { + dprintk(" bad ruleno %d\n", ruleno); + return 0; + } + + rule = map->rules[ruleno]; + result_len = 0; + w = a; + o = b; + + for (step = 0; step < rule->len; step++) { + int firstn = 0; + struct crush_rule_step *curstep = &rule->steps[step]; + + switch (curstep->op) { + case CRUSH_RULE_TAKE: + w[0] = curstep->arg1; + wsize = 1; + break; + + case CRUSH_RULE_SET_CHOOSE_TRIES: + if (curstep->arg1 > 0) + choose_tries = curstep->arg1; + break; + + case CRUSH_RULE_SET_CHOOSELEAF_TRIES: + if (curstep->arg1 > 0) + choose_leaf_tries = curstep->arg1; + break; + + case CRUSH_RULE_SET_CHOOSE_LOCAL_TRIES: + if (curstep->arg1 >= 0) + choose_local_retries = curstep->arg1; + break; + + case CRUSH_RULE_SET_CHOOSE_LOCAL_FALLBACK_TRIES: + if (curstep->arg1 >= 0) + choose_local_fallback_retries = curstep->arg1; + break; + + case CRUSH_RULE_SET_CHOOSELEAF_VARY_R: + if (curstep->arg1 >= 0) + vary_r = curstep->arg1; + break; + + case CRUSH_RULE_CHOOSELEAF_FIRSTN: + case CRUSH_RULE_CHOOSE_FIRSTN: + firstn = 1; + /* fall through */ + case CRUSH_RULE_CHOOSELEAF_INDEP: + case CRUSH_RULE_CHOOSE_INDEP: + if (wsize == 0) + break; + + recurse_to_leaf = + curstep->op == + CRUSH_RULE_CHOOSELEAF_FIRSTN || + curstep->op == + CRUSH_RULE_CHOOSELEAF_INDEP; + + /* reset output */ + osize = 0; + + for (i = 0; i < wsize; i++) { + /* + * see CRUSH_N, CRUSH_N_MINUS macros. + * basically, numrep <= 0 means relative to + * the provided result_max + */ + numrep = curstep->arg1; + if (numrep <= 0) { + numrep += result_max; + if (numrep <= 0) + continue; + } + j = 0; + if (firstn) { + int recurse_tries; + if (choose_leaf_tries) + recurse_tries = + choose_leaf_tries; + else if (map->chooseleaf_descend_once) + recurse_tries = 1; + else + recurse_tries = choose_tries; + osize += crush_choose_firstn( + map, + map->buckets[-1-w[i]], + weight, weight_max, + x, numrep, + curstep->arg2, + o+osize, j, + result_max-osize, + choose_tries, + recurse_tries, + choose_local_retries, + choose_local_fallback_retries, + recurse_to_leaf, + vary_r, + c+osize, + 0); + } else { + out_size = ((numrep < (result_max-osize)) ? + numrep : (result_max-osize)); + crush_choose_indep( + map, + map->buckets[-1-w[i]], + weight, weight_max, + x, out_size, numrep, + curstep->arg2, + o+osize, j, + choose_tries, + choose_leaf_tries ? + choose_leaf_tries : 1, + recurse_to_leaf, + c+osize, + 0); + osize += out_size; + } + } + + if (recurse_to_leaf) + /* copy final _leaf_ values to output set */ + memcpy(o, c, osize*sizeof(*o)); + + /* swap o and w arrays */ + tmp = o; + o = w; + w = tmp; + wsize = osize; + break; + + + case CRUSH_RULE_EMIT: + for (i = 0; i < wsize && result_len < result_max; i++) { + result[result_len] = w[i]; + result_len++; + } + wsize = 0; + break; + + default: + dprintk(" unknown op %d at step %d\n", + curstep->op, step); + break; + } + } + return result_len; +} + + |