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Add t/helper/test-lazy-init-name-hash.c test code to demonstrate performance times for lazy_init_name_hash() using the original single-threaded and the new multi-threaded code paths. Includes a --dump option to dump the created hashmaps to stdout. You can use this to run both code paths and confirm that they generate the same hashmaps. Includes a --analyze option to analyze performance of both code paths over a range of index sizes to help you find a lower bound for the LAZY_THREAD_COST in name-hash.c. For example, passing "-a 4000" will set "istate.cache_nr" to 4000 and then try the multi-threaded code -- probably giving 2 threads with 2000 entries each. It will then run both the single-threaded (1x4000) and the multi-threaded (2x2000) and compare the times. It will then repeat the test with 8000, 12000, and etc. so that you can see the cross over. Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
265 lines
6.2 KiB
C
265 lines
6.2 KiB
C
#include "cache.h"
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#include "parse-options.h"
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static int single;
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static int multi;
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static int count = 1;
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static int dump;
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static int perf;
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static int analyze;
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static int analyze_step;
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/*
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* Dump the contents of the "dir" and "name" hash tables to stdout.
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* If you sort the result, you can compare it with the other type
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* mode and verify that both single and multi produce the same set.
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*/
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static void dump_run(void)
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{
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struct hashmap_iter iter_dir;
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struct hashmap_iter iter_cache;
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/* Stolen from name-hash.c */
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struct dir_entry {
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struct hashmap_entry ent;
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struct dir_entry *parent;
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int nr;
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unsigned int namelen;
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char name[FLEX_ARRAY];
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};
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struct dir_entry *dir;
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struct cache_entry *ce;
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read_cache();
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if (single) {
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test_lazy_init_name_hash(&the_index, 0);
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} else {
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int nr_threads_used = test_lazy_init_name_hash(&the_index, 1);
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if (!nr_threads_used)
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die("non-threaded code path used");
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}
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dir = hashmap_iter_first(&the_index.dir_hash, &iter_dir);
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while (dir) {
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printf("dir %08x %7d %s\n", dir->ent.hash, dir->nr, dir->name);
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dir = hashmap_iter_next(&iter_dir);
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}
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ce = hashmap_iter_first(&the_index.name_hash, &iter_cache);
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while (ce) {
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printf("name %08x %s\n", ce->ent.hash, ce->name);
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ce = hashmap_iter_next(&iter_cache);
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}
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discard_cache();
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}
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/*
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* Run the single or multi threaded version "count" times and
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* report on the time taken.
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*/
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static uint64_t time_runs(int try_threaded)
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{
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uint64_t t0, t1, t2;
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uint64_t sum = 0;
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uint64_t avg;
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int nr_threads_used;
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int i;
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for (i = 0; i < count; i++) {
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t0 = getnanotime();
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read_cache();
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t1 = getnanotime();
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nr_threads_used = test_lazy_init_name_hash(&the_index, try_threaded);
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t2 = getnanotime();
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sum += (t2 - t1);
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if (try_threaded && !nr_threads_used)
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die("non-threaded code path used");
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if (nr_threads_used)
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printf("%f %f %d multi %d\n",
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((double)(t1 - t0))/1000000000,
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((double)(t2 - t1))/1000000000,
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the_index.cache_nr,
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nr_threads_used);
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else
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printf("%f %f %d single\n",
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((double)(t1 - t0))/1000000000,
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((double)(t2 - t1))/1000000000,
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the_index.cache_nr);
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fflush(stdout);
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discard_cache();
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}
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avg = sum / count;
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if (count > 1)
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printf("avg %f %s\n",
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(double)avg/1000000000,
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(try_threaded) ? "multi" : "single");
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return avg;
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}
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/*
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* Try a series of runs varying the "istate->cache_nr" and
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* try to find a good value for the multi-threaded criteria.
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*/
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static void analyze_run(void)
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{
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uint64_t t1s, t1m, t2s, t2m;
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int cache_nr_limit;
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int nr_threads_used;
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int i;
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int nr;
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read_cache();
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cache_nr_limit = the_index.cache_nr;
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discard_cache();
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nr = analyze;
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while (1) {
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uint64_t sum_single = 0;
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uint64_t sum_multi = 0;
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uint64_t avg_single;
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uint64_t avg_multi;
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if (nr > cache_nr_limit)
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nr = cache_nr_limit;
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for (i = 0; i < count; i++) {
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read_cache();
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the_index.cache_nr = nr; /* cheap truncate of index */
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t1s = getnanotime();
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test_lazy_init_name_hash(&the_index, 0);
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t2s = getnanotime();
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sum_single += (t2s - t1s);
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the_index.cache_nr = cache_nr_limit;
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discard_cache();
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read_cache();
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the_index.cache_nr = nr; /* cheap truncate of index */
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t1m = getnanotime();
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nr_threads_used = test_lazy_init_name_hash(&the_index, 1);
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t2m = getnanotime();
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sum_multi += (t2m - t1m);
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the_index.cache_nr = cache_nr_limit;
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discard_cache();
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if (!nr_threads_used)
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printf(" [size %8d] [single %f] non-threaded code path used\n",
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nr, ((double)(t2s - t1s))/1000000000);
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else
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printf(" [size %8d] [single %f] %c [multi %f %d]\n",
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nr,
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((double)(t2s - t1s))/1000000000,
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(((t2s - t1s) < (t2m - t1m)) ? '<' : '>'),
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((double)(t2m - t1m))/1000000000,
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nr_threads_used);
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fflush(stdout);
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}
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if (count > 1) {
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avg_single = sum_single / count;
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avg_multi = sum_multi / count;
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if (!nr_threads_used)
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printf("avg [size %8d] [single %f]\n",
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nr,
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(double)avg_single/1000000000);
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else
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printf("avg [size %8d] [single %f] %c [multi %f %d]\n",
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nr,
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(double)avg_single/1000000000,
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(avg_single < avg_multi ? '<' : '>'),
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(double)avg_multi/1000000000,
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nr_threads_used);
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fflush(stdout);
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}
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if (nr >= cache_nr_limit)
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return;
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nr += analyze_step;
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}
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}
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int cmd_main(int argc, const char **argv)
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{
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const char *usage[] = {
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"test-lazy-init-name-hash -d (-s | -m)",
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"test-lazy-init-name-hash -p [-c c]",
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"test-lazy-init-name-hash -a a [--step s] [-c c]",
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"test-lazy-init-name-hash (-s | -m) [-c c]",
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"test-lazy-init-name-hash -s -m [-c c]",
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NULL
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};
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struct option options[] = {
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OPT_BOOL('s', "single", &single, "run single-threaded code"),
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OPT_BOOL('m', "multi", &multi, "run multi-threaded code"),
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OPT_INTEGER('c', "count", &count, "number of passes"),
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OPT_BOOL('d', "dump", &dump, "dump hash tables"),
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OPT_BOOL('p', "perf", &perf, "compare single vs multi"),
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OPT_INTEGER('a', "analyze", &analyze, "analyze different multi sizes"),
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OPT_INTEGER(0, "step", &analyze_step, "analyze step factor"),
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OPT_END(),
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};
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const char *prefix;
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uint64_t avg_single, avg_multi;
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prefix = setup_git_directory();
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argc = parse_options(argc, argv, prefix, options, usage, 0);
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/*
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* istate->dir_hash is only created when ignore_case is set.
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*/
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ignore_case = 1;
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if (dump) {
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if (perf || analyze > 0)
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die("cannot combine dump, perf, or analyze");
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if (count > 1)
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die("count not valid with dump");
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if (single && multi)
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die("cannot use both single and multi with dump");
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if (!single && !multi)
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die("dump requires either single or multi");
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dump_run();
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return 0;
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}
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if (perf) {
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if (analyze > 0)
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die("cannot combine dump, perf, or analyze");
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if (single || multi)
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die("cannot use single or multi with perf");
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avg_single = time_runs(0);
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avg_multi = time_runs(1);
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if (avg_multi > avg_single)
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die("multi is slower");
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return 0;
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}
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if (analyze) {
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if (analyze < 500)
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die("analyze must be at least 500");
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if (!analyze_step)
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analyze_step = analyze;
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if (single || multi)
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die("cannot use single or multi with analyze");
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analyze_run();
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return 0;
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}
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if (!single && !multi)
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die("require either -s or -m or both");
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if (single)
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time_runs(0);
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if (multi)
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time_runs(1);
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return 0;
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}
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