Add sample zipf distribution randomizer
Instead of just doing purely random IO where each block is
touched exactly (or close to, depending on random map) once,
add a zipf distribution scheme where a selectable theta
defines the spread and frequency of blocks read/written.
Committing this so I don't lose it. Needs a few changes,
for instance we need to hash the zipf output so that
the spread doesn't always just favor the lower LBA range.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/options.c b/options.c
index 380df36..05a6a50 100644
--- a/options.c
+++ b/options.c
@@ -728,6 +728,29 @@
}
#endif
+static int str_random_distribution_cb(void *data, const char *str)
+{
+ struct thread_data *td = data;
+ double val;
+ char *nr;
+
+ if (td->o.random_distribution == FIO_RAND_DIST_RANDOM)
+ return 0;
+
+ nr = get_opt_postfix(str);
+ if (!nr)
+ val = 0.6;
+ else if (!str_to_float(nr, &val)) {
+ log_err("fio: random postfix parsing failed\n");
+ free(nr);
+ return 1;
+ }
+
+ td->o.zipf_theta = val;
+ free(nr);
+ return 0;
+}
+
static int check_dir(struct thread_data *td, char *fname)
{
#if 0
@@ -1473,6 +1496,24 @@
.def = "0",
},
{
+ .name = "random_distribution",
+ .type = FIO_OPT_STR,
+ .off1 = td_var_offset(random_distribution),
+ .cb = str_random_distribution_cb,
+ .help = "Random offset distribution generator",
+ .def = "random",
+ .posval = {
+ { .ival = "random",
+ .oval = FIO_RAND_DIST_RANDOM,
+ .help = "Completely random",
+ },
+ { .ival = "zipf",
+ .oval = FIO_RAND_DIST_ZIPF,
+ .help = "Zipf distribution",
+ },
+ },
+ },
+ {
.name = "nrfiles",
.alias = "nr_files",
.type = FIO_OPT_INT,