wsim: Per-client prng pool for miscellaneous randoms

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

3 files changed, 18 insertions, 10 deletions

diff --git a/benchmarks/gem_wsim.c b/benchmarks/gem_wsim.c
index 8023cd0e..2a8af7ba 100644
--- a/benchmarks/gem_wsim.c
+++ b/benchmarks/gem_wsim.c
@@ -105,6 +105,8 @@ struct workload
 	unsigned int nr_steps;
 	struct w_step *steps;
 
+	uint32_t prng;
+
 	struct timespec repeat_start;
 
 	int pipe[2];
@@ -628,6 +630,8 @@ prepare_workload(unsigned int id, struct workload *wrk, unsigned int flags)
 	struct w_step *w;
 	int i;
 
+	wrk->prng = rand();
+
 	if (flags & INITVCSRR)
 		wrk->vcs_rr = id & 1;
 
@@ -818,7 +822,7 @@ __rt_balance(const struct workload_balancer *balancer,
 	else if (qd[VCS2] < qd[VCS1])
 		n = 1;
 	else if (random)
-		n = hars_petruska_f54_1_random_unsafe() & 1;
+		n = hars_petruska_f54_1_random(&wrk->prng) & 1;
 	else
 		n = wrk->vcs_rr;
 
@@ -845,7 +849,6 @@ static enum intel_engine_id
 rtr_balance(const struct workload_balancer *balancer,
 	   struct workload *wrk, struct w_step *w)
 {
-
 	return __rt_balance(balancer, wrk, w, true);
 }
 
diff --git a/lib/igt_rand.c b/lib/igt_rand.c
index a3298a9f..b8d3a92c 100644
--- a/lib/igt_rand.c
+++ b/lib/igt_rand.c
@@ -1,19 +1,22 @@
 #include "igt_rand.h"
 
-static uint32_t state = 0x12345678;
+static uint32_t global = 0x12345678;
 
-uint32_t
-hars_petruska_f54_1_random_seed(uint32_t new_state)
+uint32_t hars_petruska_f54_1_random_seed(uint32_t new_state)
 {
-	uint32_t old_state = state;
-	state = new_state;
+	uint32_t old_state = global;
+	global = new_state;
 	return old_state;
 }
 
-uint32_t
-hars_petruska_f54_1_random_unsafe(void)
+uint32_t hars_petruska_f54_1_random(uint32_t *s)
 {
 #define rol(x,k) ((x << k) | (x >> (32-k)))
-	return state = (state ^ rol (state, 5) ^ rol (state, 24)) + 0x37798849;
+	return *s = (*s ^ rol(*s, 5) ^ rol(*s, 24)) + 0x37798849;
 #undef rol
 }
+
+uint32_t hars_petruska_f54_1_random_unsafe(void)
+{
+	return hars_petruska_f54_1_random(&global);
+}
diff --git a/lib/igt_rand.h b/lib/igt_rand.h
index d676752d..f664af41 100644
--- a/lib/igt_rand.h
+++ b/lib/igt_rand.h
@@ -26,6 +26,8 @@
 
 #include <stdint.h>
 
+uint32_t hars_petruska_f54_1_random(uint32_t *state);
+
 uint32_t hars_petruska_f54_1_random_seed(uint32_t seed);
 uint32_t hars_petruska_f54_1_random_unsafe(void);