diff options
| -rw-r--r-- | Documentation/technical/api-hashmap.txt | 22 | ||||
| -rw-r--r-- | Makefile | 1 | ||||
| -rw-r--r-- | cache.h | 1 | ||||
| -rw-r--r-- | hashmap.c | 29 | ||||
| -rw-r--r-- | hashmap.h | 25 | ||||
| -rw-r--r-- | name-hash.c | 495 | ||||
| -rw-r--r-- | t/helper/.gitignore | 1 | ||||
| -rw-r--r-- | t/helper/test-lazy-init-name-hash.c | 264 | ||||
| -rw-r--r-- | t/perf/p0004-lazy-init-name-hash.sh | 19 |
9 files changed, 848 insertions, 9 deletions
diff --git a/Documentation/technical/api-hashmap.txt b/Documentation/technical/api-hashmap.txt index a3f020c..ccc634b 100644 --- a/Documentation/technical/api-hashmap.txt +++ b/Documentation/technical/api-hashmap.txt @@ -21,6 +21,9 @@ that the hashmap is initialized. It may also be useful for statistical purposes `cmpfn` stores the comparison function specified in `hashmap_init()`. In advanced scenarios, it may be useful to change this, e.g. to switch between case-sensitive and case-insensitive lookup. ++ +When `disallow_rehash` is set, automatic rehashes are prevented during inserts +and deletes. `struct hashmap_entry`:: @@ -57,6 +60,7 @@ Functions `unsigned int strihash(const char *buf)`:: `unsigned int memhash(const void *buf, size_t len)`:: `unsigned int memihash(const void *buf, size_t len)`:: +`unsigned int memihash_cont(unsigned int hash_seed, const void *buf, size_t len)`:: Ready-to-use hash functions for strings, using the FNV-1 algorithm (see http://www.isthe.com/chongo/tech/comp/fnv). @@ -65,6 +69,9 @@ Functions `memihash` operate on arbitrary-length memory. + `strihash` and `memihash` are case insensitive versions. ++ +`memihash_cont` is a variant of `memihash` that allows a computation to be +continued with another chunk of data. `unsigned int sha1hash(const unsigned char *sha1)`:: @@ -184,6 +191,21 @@ passed to `hashmap_cmp_fn` to decide whether the entry matches the key. + Returns the removed entry, or NULL if not found. +`void hashmap_disallow_rehash(struct hashmap *map, unsigned value)`:: + + Disallow/allow automatic rehashing of the hashmap during inserts + and deletes. ++ +This is useful if the caller knows that the hashmap will be accessed +by multiple threads. ++ +The caller is still responsible for any necessary locking; this simply +prevents unexpected rehashing. The caller is also responsible for properly +sizing the initial hashmap to ensure good performance. ++ +A call to allow rehashing does not force a rehash; that might happen +with the next insert or delete. + `void hashmap_iter_init(struct hashmap *map, struct hashmap_iter *iter)`:: `void *hashmap_iter_next(struct hashmap_iter *iter)`:: `void *hashmap_iter_first(struct hashmap *map, struct hashmap_iter *iter)`:: @@ -621,6 +621,7 @@ TEST_PROGRAMS_NEED_X += test-fake-ssh TEST_PROGRAMS_NEED_X += test-genrandom TEST_PROGRAMS_NEED_X += test-hashmap TEST_PROGRAMS_NEED_X += test-index-version +TEST_PROGRAMS_NEED_X += test-lazy-init-name-hash TEST_PROGRAMS_NEED_X += test-line-buffer TEST_PROGRAMS_NEED_X += test-match-trees TEST_PROGRAMS_NEED_X += test-mergesort @@ -343,6 +343,7 @@ struct index_state { extern struct index_state the_index; /* Name hashing */ +extern int test_lazy_init_name_hash(struct index_state *istate, int try_threaded); extern void add_name_hash(struct index_state *istate, struct cache_entry *ce); extern void remove_name_hash(struct index_state *istate, struct cache_entry *ce); extern void free_name_hash(struct index_state *istate); @@ -50,6 +50,23 @@ unsigned int memihash(const void *buf, size_t len) return hash; } +/* + * Incoporate another chunk of data into a memihash + * computation. + */ +unsigned int memihash_cont(unsigned int hash_seed, const void *buf, size_t len) +{ + unsigned int hash = hash_seed; + unsigned char *ucbuf = (unsigned char *) buf; + while (len--) { + unsigned int c = *ucbuf++; + if (c >= 'a' && c <= 'z') + c -= 'a' - 'A'; + hash = (hash * FNV32_PRIME) ^ c; + } + return hash; +} + #define HASHMAP_INITIAL_SIZE 64 /* grow / shrink by 2^2 */ #define HASHMAP_RESIZE_BITS 2 @@ -87,11 +104,19 @@ static inline unsigned int bucket(const struct hashmap *map, return key->hash & (map->tablesize - 1); } +int hashmap_bucket(const struct hashmap *map, unsigned int hash) +{ + return hash & (map->tablesize - 1); +} + static void rehash(struct hashmap *map, unsigned int newsize) { unsigned int i, oldsize = map->tablesize; struct hashmap_entry **oldtable = map->table; + if (map->disallow_rehash) + return; + alloc_table(map, newsize); for (i = 0; i < oldsize; i++) { struct hashmap_entry *e = oldtable[i]; @@ -124,7 +149,9 @@ void hashmap_init(struct hashmap *map, hashmap_cmp_fn equals_function, size_t initial_size) { unsigned int size = HASHMAP_INITIAL_SIZE; - map->size = 0; + + memset(map, 0, sizeof(*map)); + map->cmpfn = equals_function ? equals_function : always_equal; /* calculate initial table size and allocate the table */ @@ -12,6 +12,7 @@ extern unsigned int strhash(const char *buf); extern unsigned int strihash(const char *buf); extern unsigned int memhash(const void *buf, size_t len); extern unsigned int memihash(const void *buf, size_t len); +extern unsigned int memihash_cont(unsigned int hash_seed, const void *buf, size_t len); static inline unsigned int sha1hash(const unsigned char *sha1) { @@ -38,6 +39,7 @@ struct hashmap { struct hashmap_entry **table; hashmap_cmp_fn cmpfn; unsigned int size, tablesize, grow_at, shrink_at; + unsigned disallow_rehash : 1; }; struct hashmap_iter { @@ -76,6 +78,29 @@ static inline void *hashmap_get_from_hash(const struct hashmap *map, return hashmap_get(map, &key, keydata); } +int hashmap_bucket(const struct hashmap *map, unsigned int hash); + +/* + * Disallow/allow rehashing of the hashmap. + * This is useful if the caller knows that the hashmap + * needs multi-threaded access. The caller is still + * required to guard/lock searches and inserts in a + * manner appropriate to their usage. This simply + * prevents the table from being unexpectedly re-mapped. + * + * If is up to the caller to ensure that the hashmap is + * initialized to a reasonable size to prevent poor + * performance. + * + * When value=1, prevent future rehashes on adds and deleted. + * When value=0, allow future rehahses. This DOES NOT force + * a rehash now. + */ +static inline void hashmap_disallow_rehash(struct hashmap *map, unsigned value) +{ + map->disallow_rehash = value; +} + /* hashmap_iter functions */ extern void hashmap_iter_init(struct hashmap *map, struct hashmap_iter *iter); diff --git a/name-hash.c b/name-hash.c index 6d9f23e..cac313c 100644 --- a/name-hash.c +++ b/name-hash.c @@ -23,15 +23,21 @@ static int dir_entry_cmp(const struct dir_entry *e1, name ? name : e2->name, e1->namelen); } -static struct dir_entry *find_dir_entry(struct index_state *istate, - const char *name, unsigned int namelen) +static struct dir_entry *find_dir_entry__hash(struct index_state *istate, + const char *name, unsigned int namelen, unsigned int hash) { struct dir_entry key; - hashmap_entry_init(&key, memihash(name, namelen)); + hashmap_entry_init(&key, hash); key.namelen = namelen; return hashmap_get(&istate->dir_hash, &key, name); } +static struct dir_entry *find_dir_entry(struct index_state *istate, + const char *name, unsigned int namelen) +{ + return find_dir_entry__hash(istate, name, namelen, memihash(name, namelen)); +} + static struct dir_entry *hash_dir_entry(struct index_state *istate, struct cache_entry *ce, int namelen) { @@ -112,20 +118,493 @@ static int cache_entry_cmp(const struct cache_entry *ce1, return remove ? !(ce1 == ce2) : 0; } -static void lazy_init_name_hash(struct index_state *istate) +static int lazy_try_threaded = 1; +static int lazy_nr_dir_threads; + +#ifdef NO_PTHREADS + +static inline int lookup_lazy_params(struct index_state *istate) { - int nr; + return 0; +} + +static inline void threaded_lazy_init_name_hash( + struct index_state *istate) +{ +} + +#else + +#include "thread-utils.h" + +/* + * Set a minimum number of cache_entries that we will handle per + * thread and use that to decide how many threads to run (upto + * the number on the system). + * + * For guidance setting the lower per-thread bound, see: + * t/helper/test-lazy-init-name-hash --analyze + */ +#define LAZY_THREAD_COST (2000) + +/* + * We use n mutexes to guard n partitions of the "istate->dir_hash" + * hashtable. Since "find" and "insert" operations will hash to a + * particular bucket and modify/search a single chain, we can say + * that "all chains mod n" are guarded by the same mutex -- rather + * than having a single mutex to guard the entire table. (This does + * require that we disable "rehashing" on the hashtable.) + * + * So, a larger value here decreases the probability of a collision + * and the time that each thread must wait for the mutex. + */ +#define LAZY_MAX_MUTEX (32) + +static pthread_mutex_t *lazy_dir_mutex_array; + +/* + * An array of lazy_entry items is used by the n threads in + * the directory parse (first) phase to (lock-free) store the + * intermediate results. These values are then referenced by + * the 2 threads in the second phase. + */ +struct lazy_entry { + struct dir_entry *dir; + unsigned int hash_dir; + unsigned int hash_name; +}; + +/* + * Decide if we want to use threads (if available) to load + * the hash tables. We set "lazy_nr_dir_threads" to zero when + * it is not worth it. + */ +static int lookup_lazy_params(struct index_state *istate) +{ + int nr_cpus; + + lazy_nr_dir_threads = 0; + + if (!lazy_try_threaded) + return 0; + + /* + * If we are respecting case, just use the original + * code to build the "istate->name_hash". We don't + * need the complexity here. + */ + if (!ignore_case) + return 0; + + nr_cpus = online_cpus(); + if (nr_cpus < 2) + return 0; + + if (istate->cache_nr < 2 * LAZY_THREAD_COST) + return 0; + + if (istate->cache_nr < nr_cpus * LAZY_THREAD_COST) + nr_cpus = istate->cache_nr / LAZY_THREAD_COST; + lazy_nr_dir_threads = nr_cpus; + return lazy_nr_dir_threads; +} + +/* + * Initialize n mutexes for use when searching and inserting + * into "istate->dir_hash". All "dir" threads are trying + * to insert partial pathnames into the hash as they iterate + * over their portions of the index, so lock contention is + * high. + * + * However, the hashmap is going to put items into bucket + * chains based on their hash values. Use that to create n + * mutexes and lock on mutex[bucket(hash) % n]. This will + * decrease the collision rate by (hopefully) by a factor of n. + */ +static void init_dir_mutex(void) +{ + int j; + + lazy_dir_mutex_array = xcalloc(LAZY_MAX_MUTEX, sizeof(pthread_mutex_t)); + + for (j = 0; j < LAZY_MAX_MUTEX; j++) + init_recursive_mutex(&lazy_dir_mutex_array[j]); +} + +static void cleanup_dir_mutex(void) +{ + int j; + + for (j = 0; j < LAZY_MAX_MUTEX; j++) + pthread_mutex_destroy(&lazy_dir_mutex_array[j]); + + free(lazy_dir_mutex_array); +} + +static void lock_dir_mutex(int j) +{ + pthread_mutex_lock(&lazy_dir_mutex_array[j]); +} + +static void unlock_dir_mutex(int j) +{ + pthread_mutex_unlock(&lazy_dir_mutex_array[j]); +} + +static inline int compute_dir_lock_nr( + const struct hashmap *map, + unsigned int hash) +{ + return hashmap_bucket(map, hash) % LAZY_MAX_MUTEX; +} + +static struct dir_entry *hash_dir_entry_with_parent_and_prefix( + struct index_state *istate, + struct dir_entry *parent, + struct strbuf *prefix) +{ + struct dir_entry *dir; + unsigned int hash; + int lock_nr; + + /* + * Either we have a parent directory and path with slash(es) + * or the directory is an immediate child of the root directory. + */ + assert((parent != NULL) ^ (strchr(prefix->buf, '/') == NULL)); + + if (parent) + hash = memihash_cont(parent->ent.hash, + prefix->buf + parent->namelen, + prefix->len - parent->namelen); + else + hash = memihash(prefix->buf, prefix->len); + + lock_nr = compute_dir_lock_nr(&istate->dir_hash, hash); + lock_dir_mutex(lock_nr); + + dir = find_dir_entry__hash(istate, prefix->buf, prefix->len, hash); + if (!dir) { + FLEX_ALLOC_MEM(dir, name, prefix->buf, prefix->len); + hashmap_entry_init(dir, hash); + dir->namelen = prefix->len; + dir->parent = parent; + hashmap_add(&istate->dir_hash, dir); + + if (parent) { + unlock_dir_mutex(lock_nr); + + /* All I really need here is an InterlockedIncrement(&(parent->nr)) */ + lock_nr = compute_dir_lock_nr(&istate->dir_hash, parent->ent.hash); + lock_dir_mutex(lock_nr); + parent->nr++; + } + } + + unlock_dir_mutex(lock_nr); + return dir; +} + +/* + * handle_range_1() and handle_range_dir() are derived from + * clear_ce_flags_1() and clear_ce_flags_dir() in unpack-trees.c + * and handle the iteration over the entire array of index entries. + * They use recursion for adjacent entries in the same parent + * directory. + */ +static int handle_range_1( + struct index_state *istate, + int k_start, + int k_end, + struct dir_entry *parent, + struct strbuf *prefix, + struct lazy_entry *lazy_entries); + +static int handle_range_dir( + struct index_state *istate, + int k_start, + int k_end, + struct dir_entry *parent, + struct strbuf *prefix, + struct lazy_entry *lazy_entries, + struct dir_entry **dir_new_out) +{ + int rc, k; + int input_prefix_len = prefix->len; + struct dir_entry *dir_new; + + dir_new = hash_dir_entry_with_parent_and_prefix(istate, parent, prefix); + + strbuf_addch(prefix, '/'); + + /* + * Scan forward in the index array for index entries having the same + * path prefix (that are also in this directory). + */ + if (strncmp(istate->cache[k_start + 1]->name, prefix->buf, prefix->len) > 0) + k = k_start + 1; + else if (strncmp(istate->cache[k_end - 1]->name, prefix->buf, prefix->len) == 0) + k = k_end; + else { + int begin = k_start; + int end = k_end; + while (begin < end) { + int mid = (begin + end) >> 1; + int cmp = strncmp(istate->cache[mid]->name, prefix->buf, prefix->len); + if (cmp == 0) /* mid has same prefix; look in second part */ + begin = mid + 1; + else if (cmp > 0) /* mid is past group; look in first part */ + end = mid; + else + die("cache entry out of order"); + } + k = begin; + } + + /* + * Recurse and process what we can of this subset [k_start, k). + */ + rc = handle_range_1(istate, k_start, k, dir_new, prefix, lazy_entries); + + strbuf_setlen(prefix, input_prefix_len); + + *dir_new_out = dir_new; + return rc; +} + +static int handle_range_1( + struct index_state *istate, + int k_start, + int k_end, + struct dir_entry *parent, + struct strbuf *prefix, + struct lazy_entry *lazy_entries) +{ + int input_prefix_len = prefix->len; + int k = k_start; + + while (k < k_end) { + struct cache_entry *ce_k = istate->cache[k]; + const char *name, *slash; + + if (prefix->len && strncmp(ce_k->name, prefix->buf, prefix->len)) + break; + + name = ce_k->name + prefix->len; + slash = strchr(name, '/'); + + if (slash) { + int len = slash - name; + int processed; + struct dir_entry *dir_new; + + strbuf_add(prefix, name, len); + processed = handle_range_dir(istate, k, k_end, parent, prefix, lazy_entries, &dir_new); + if (processed) { + k += processed; + strbuf_setlen(prefix, input_prefix_len); + continue; + } + + strbuf_addch(prefix, '/'); + processed = handle_range_1(istate, k, k_end, dir_new, prefix, lazy_entries); + k += processed; + strbuf_setlen(prefix, input_prefix_len); + continue; + } + + /* + * It is too expensive to take a lock to insert "ce_k" + * into "istate->name_hash" and increment the ref-count + * on the "parent" dir. So we defer actually updating + * permanent data structures until phase 2 (where we + * can change the locking requirements) and simply + * accumulate our current results into the lazy_entries + * data array). + * + * We do not need to lock the lazy_entries array because + * we have exclusive access to the cells in the range + * [k_start,k_end) that this thread was given. + */ + lazy_entries[k].dir = parent; + if (parent) { + lazy_entries[k].hash_name = memihash_cont( + parent->ent.hash, + ce_k->name + parent->namelen, + ce_namelen(ce_k) - parent->namelen); + lazy_entries[k].hash_dir = parent->ent.hash; + } else { + lazy_entries[k].hash_name = memihash(ce_k->name, ce_namelen(ce_k)); + } + + k++; + } + + return k - k_start; +} + +struct lazy_dir_thread_data { + pthread_t pthread; + struct index_state *istate; + struct lazy_entry *lazy_entries; + int k_start; + int k_end; +}; + +static void *lazy_dir_thread_proc(void *_data) +{ + struct lazy_dir_thread_data *d = _data; + struct strbuf prefix = STRBUF_INIT; + handle_range_1(d->istate, d->k_start, d->k_end, NULL, &prefix, d->lazy_entries); + strbuf_release(&prefix); + return NULL; +} + +struct lazy_name_thread_data { + pthread_t pthread; + struct index_state *istate; + struct lazy_entry *lazy_entries; +}; + +static void *lazy_name_thread_proc(void *_data) +{ + struct lazy_name_thread_data *d = _data; + int k; + + for (k = 0; k < d->istate->cache_nr; k++) { + struct cache_entry *ce_k = d->istate->cache[k]; + ce_k->ce_flags |= CE_HASHED; + hashmap_entry_init(ce_k, d->lazy_entries[k].hash_name); + hashmap_add(&d->istate->name_hash, ce_k); + } + + return NULL; +} + +static inline void lazy_update_dir_ref_counts( + struct index_state *istate, + struct lazy_entry *lazy_entries) +{ + int k; + + for (k = 0; k < istate->cache_nr; k++) { + if (lazy_entries[k].dir) + lazy_entries[k].dir->nr++; + } +} + +static void threaded_lazy_init_name_hash( + struct index_state *istate) +{ + int nr_each; + int k_start; + int t; + struct lazy_entry *lazy_entries; + struct lazy_dir_thread_data *td_dir; + struct lazy_name_thread_data *td_name; + + k_start = 0; + nr_each = DIV_ROUND_UP(istate->cache_nr, lazy_nr_dir_threads); + + lazy_entries = xcalloc(istate->cache_nr, sizeof(struct lazy_entry)); + td_dir = xcalloc(lazy_nr_dir_threads, sizeof(struct lazy_dir_thread_data)); + td_name = xcalloc(1, sizeof(struct lazy_name_thread_data)); + + init_dir_mutex(); + + /* + * Phase 1: + * Build "istate->dir_hash" using n "dir" threads (and a read-only index). + */ + for (t = 0; t < lazy_nr_dir_threads; t++) { + struct lazy_dir_thread_data *td_dir_t = td_dir + t; + td_dir_t->istate = istate; + td_dir_t->lazy_entries = lazy_entries; + td_dir_t->k_start = k_start; + k_start += nr_each; + if (k_start > istate->cache_nr) + k_start = istate->cache_nr; + td_dir_t->k_end = k_start; + if (pthread_create(&td_dir_t->pthread, NULL, lazy_dir_thread_proc, td_dir_t)) + die("unable to create lazy_dir_thread"); + } + for (t = 0; t < lazy_nr_dir_threads; t++) { + struct lazy_dir_thread_data *td_dir_t = td_dir + t; + if (pthread_join(td_dir_t->pthread, NULL)) + die("unable to join lazy_dir_thread"); + } + + /* + * Phase 2: + * Iterate over all index entries and add them to the "istate->name_hash" + * using a single "name" background thread. + * (Testing showed it wasn't worth running more than 1 thread for this.) + * + * Meanwhile, finish updating the parent directory ref-counts for each + * index entry using the current thread. (This step is very fast and + * doesn't need threading.) + */ + td_name->istate = istate; + td_name->lazy_entries = lazy_entries; + if (pthread_create(&td_name->pthread, NULL, lazy_name_thread_proc, td_name)) + die("unable to create lazy_name_thread"); + + lazy_update_dir_ref_counts(istate, lazy_entries); + + if (pthread_join(td_name->pthread, NULL)) + die("unable to join lazy_name_thread"); + + cleanup_dir_mutex(); + + free(td_name); + free(td_dir); + free(lazy_entries); +} + +#endif + +static void lazy_init_name_hash(struct index_state *istate) +{ if (istate->name_hash_initialized) return; hashmap_init(&istate->name_hash, (hashmap_cmp_fn) cache_entry_cmp, istate->cache_nr); - hashmap_init(&istate->dir_hash, (hashmap_cmp_fn) dir_entry_cmp, 0); - for (nr = 0; nr < istate->cache_nr; nr++) - hash_index_entry(istate, istate->cache[nr]); + hashmap_init(&istate->dir_hash, (hashmap_cmp_fn) dir_entry_cmp, + istate->cache_nr); + + if (lookup_lazy_params(istate)) { + hashmap_disallow_rehash(&istate->dir_hash, 1); + threaded_lazy_init_name_hash(istate); + hashmap_disallow_rehash(&istate->dir_hash, 0); + } else { + int nr; + for (nr = 0; nr < istate->cache_nr; nr++) + hash_index_entry(istate, istate->cache[nr]); + } + istate->name_hash_initialized = 1; } +/* + * A test routine for t/helper/ sources. + * + * Returns the number of threads used or 0 when + * the non-threaded code path was used. + * + * Requesting threading WILL NOT override guards + * in lookup_lazy_params(). + */ +int test_lazy_init_name_hash(struct index_state *istate, int try_threaded) +{ + lazy_nr_dir_threads = 0; + lazy_try_threaded = try_threaded; + + lazy_init_name_hash(istate); + + return lazy_nr_dir_threads; +} + void add_name_hash(struct index_state *istate, struct cache_entry *ce) { if (istate->name_hash_initialized) diff --git a/t/helper/.gitignore b/t/helper/.gitignore index d6e8b36..758ed2e 100644 --- a/t/helper/.gitignore +++ b/t/helper/.gitignore @@ -11,6 +11,7 @@ /test-genrandom /test-hashmap /test-index-version +/test-lazy-init-name-hash /test-line-buffer /test-match-trees /test-mergesort diff --git a/t/helper/test-lazy-init-name-hash.c b/t/helper/test-lazy-init-name-hash.c new file mode 100644 index 0000000..6368a89 --- /dev/null +++ b/t/helper/test-lazy-init-name-hash.c @@ -0,0 +1,264 @@ +#include "cache.h" +#include "parse-options.h" + +static int single; +static int multi; +static int count = 1; +static int dump; +static int perf; +static int analyze; +static int analyze_step; + +/* + * Dump the contents of the "dir" and "name" hash tables to stdout. + * If you sort the result, you can compare it with the other type + * mode and verify that both single and multi produce the same set. + */ +static void dump_run(void) +{ + struct hashmap_iter iter_dir; + struct hashmap_iter iter_cache; + + /* Stolen from name-hash.c */ + struct dir_entry { + struct hashmap_entry ent; + struct dir_entry *parent; + int nr; + unsigned int namelen; + char name[FLEX_ARRAY]; + }; + + struct dir_entry *dir; + struct cache_entry *ce; + + read_cache(); + if (single) { + test_lazy_init_name_hash(&the_index, 0); + } else { + int nr_threads_used = test_lazy_init_name_hash(&the_index, 1); + if (!nr_threads_used) + die("non-threaded code path used"); + } + + dir = hashmap_iter_first(&the_index.dir_hash, &iter_dir); + while (dir) { + printf("dir %08x %7d %s\n", dir->ent.hash, dir->nr, dir->name); + dir = hashmap_iter_next(&iter_dir); + } + + ce = hashmap_iter_first(&the_index.name_hash, &iter_cache); + while (ce) { + printf("name %08x %s\n", ce->ent.hash, ce->name); + ce = hashmap_iter_next(&iter_cache); + } + + discard_cache(); +} + +/* + * Run the single or multi threaded version "count" times and + * report on the time taken. + */ +static uint64_t time_runs(int try_threaded) +{ + uint64_t t0, t1, t2; + uint64_t sum = 0; + uint64_t avg; + int nr_threads_used; + int i; + + for (i = 0; i < count; i++) { + t0 = getnanotime(); + read_cache(); + t1 = getnanotime(); + nr_threads_used = test_lazy_init_name_hash(&the_index, try_threaded); + t2 = getnanotime(); + + sum += (t2 - t1); + + if (try_threaded && !nr_threads_used) + die("non-threaded code path used"); + + if (nr_threads_used) + printf("%f %f %d multi %d\n", + ((double)(t1 - t0))/1000000000, + ((double)(t2 - t1))/1000000000, + the_index.cache_nr, + nr_threads_used); + else + printf("%f %f %d single\n", + ((double)(t1 - t0))/1000000000, + ((double)(t2 - t1))/1000000000, + the_index.cache_nr); + fflush(stdout); + + discard_cache(); + } + + avg = sum / count; + if (count > 1) + printf("avg %f %s\n", + (double)avg/1000000000, + (try_threaded) ? "multi" : "single"); + + return avg; +} + +/* + * Try a series of runs varying the "istate->cache_nr" and + * try to find a good value for the multi-threaded criteria. + */ +static void analyze_run(void) +{ + uint64_t t1s, t1m, t2s, t2m; + int cache_nr_limit; + int nr_threads_used; + int i; + int nr; + + read_cache(); + cache_nr_limit = the_index.cache_nr; + discard_cache(); + + nr = analyze; + while (1) { + uint64_t sum_single = 0; + uint64_t sum_multi = 0; + uint64_t avg_single; + uint64_t avg_multi; + + if (nr > cache_nr_limit) + nr = cache_nr_limit; + + for (i = 0; i < count; i++) { + read_cache(); + the_index.cache_nr = nr; /* cheap truncate of index */ + t1s = getnanotime(); + test_lazy_init_name_hash(&the_index, 0); + t2s = getnanotime(); + sum_single += (t2s - t1s); + the_index.cache_nr = cache_nr_limit; + discard_cache(); + + read_cache(); + the_index.cache_nr = nr; /* cheap truncate of index */ + t1m = getnanotime(); + nr_threads_used = test_lazy_init_name_hash(&the_index, 1); + t2m = getnanotime(); + sum_multi += (t2m - t1m); + the_index.cache_nr = cache_nr_limit; + discard_cache(); + + if (!nr_threads_used) + printf(" [size %8d] [single %f] non-threaded code path used\n", + nr, ((double)(t2s - t1s))/1000000000); + else + printf(" [size %8d] [single %f] %c [multi %f %d]\n", + nr, + ((double)(t2s - t1s))/1000000000, + (((t2s - t1s) < (t2m - t1m)) ? '<' : '>'), + ((double)(t2m - t1m))/1000000000, + nr_threads_used); + fflush(stdout); + } + if (count > 1) { + avg_single = sum_single / count; + avg_multi = sum_multi / count; + if (!nr_threads_used) + printf("avg [size %8d] [single %f]\n", + nr, + (double)avg_single/1000000000); + else + printf("avg [size %8d] [single %f] %c [multi %f %d]\n", + nr, + (double)avg_single/1000000000, + (avg_single < avg_multi ? '<' : '>'), + (double)avg_multi/1000000000, + nr_threads_used); + fflush(stdout); + } + + if (nr >= cache_nr_limit) + return; + nr += analyze_step; + } +} + +int cmd_main(int argc, const char **argv) +{ + const char *usage[] = { + "test-lazy-init-name-hash -d (-s | -m)", + "test-lazy-init-name-hash -p [-c c]", + "test-lazy-init-name-hash -a a [--step s] [-c c]", + "test-lazy-init-name-hash (-s | -m) [-c c]", + "test-lazy-init-name-hash -s -m [-c c]", + NULL + }; + struct option options[] = { + OPT_BOOL('s', "single", &single, "run single-threaded code"), + OPT_BOOL('m', "multi", &multi, "run multi-threaded code"), + OPT_INTEGER('c', "count", &count, "number of passes"), + OPT_BOOL('d', "dump", &dump, "dump hash tables"), + OPT_BOOL('p', "perf", &perf, "compare single vs multi"), + OPT_INTEGER('a', "analyze", &analyze, "analyze different multi sizes"), + OPT_INTEGER(0, "step", &analyze_step, "analyze step factor"), + OPT_END(), + }; + const char *prefix; + uint64_t avg_single, avg_multi; + + prefix = setup_git_directory(); + + argc = parse_options(argc, argv, prefix, options, usage, 0); + + /* + * istate->dir_hash is only created when ignore_case is set. + */ + ignore_case = 1; + + if (dump) { + if (perf || analyze > 0) + die("cannot combine dump, perf, or analyze"); + if (count > 1) + die("count not valid with dump"); + if (single && multi) + die("cannot use both single and multi with dump"); + if (!single && !multi) + die("dump requires either single or multi"); + dump_run(); + return 0; + } + + if (perf) { + if (analyze > 0) + die("cannot combine dump, perf, or analyze"); + if (single || multi) + die("cannot use single or multi with perf"); + avg_single = time_runs(0); + avg_multi = time_runs(1); + if (avg_multi > avg_single) + die("multi is slower"); + return 0; + } + + if (analyze) { + if (analyze < 500) + die("analyze must be at least 500"); + if (!analyze_step) + analyze_step = analyze; + if (single || multi) + die("cannot use single or multi with analyze"); + analyze_run(); + return 0; + } + + if (!single && !multi) + die("require either -s or -m or both"); + + if (single) + time_runs(0); + if (multi) + time_runs(1); + + return 0; +} diff --git a/t/perf/p0004-lazy-init-name-hash.sh b/t/perf/p0004-lazy-init-name-hash.sh new file mode 100644 index 0000000..5afa8c8 --- /dev/null +++ b/t/perf/p0004-lazy-init-name-hash.sh @@ -0,0 +1,19 @@ +#!/bin/sh + +test_description='Tests multi-threaded lazy_init_name_hash' +. ./perf-lib.sh + +test_perf_large_repo +test_checkout_worktree + +test_expect_success 'verify both methods build the same hashmaps' ' + $GIT_BUILD_DIR/t/helper/test-lazy-init-name-hash$X --dump --single | sort >out.single && + $GIT_BUILD_DIR/t/helper/test-lazy-init-name-hash$X --dump --multi | sort >out.multi && + test_cmp out.single out.multi +' + +test_expect_success 'multithreaded should be faster' ' + $GIT_BUILD_DIR/t/helper/test-lazy-init-name-hash$X --perf >out.perf +' + +test_done |