From: Jeff Hostetler <jeffhost@xxxxxxxxxxxxx>
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@xxxxxxxxxxxxx>
---
Makefile | 1 +
cache.h | 1 +
t/helper/test-lazy-init-name-hash.c | 264 ++++++++++++++++++++++++++++++++++++
3 files changed, 266 insertions(+)
create mode 100644 t/helper/test-lazy-init-name-hash.c
diff --git a/Makefile b/Makefile
index 9ec6065..5fb46c8 100644
--- a/Makefile
+++ b/Makefile
@@ -616,6 +616,7 @@ 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
diff --git a/cache.h b/cache.h
index 80b6372..6a72f6a 100644
--- a/cache.h
+++ b/cache.h
@@ -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);
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..0769e17
--- /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.
+ */
+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.
+ */
+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.
+ */
+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;
+}
--
2.7.4