From: Jens Axboe <axboe@kernel.dk>
Date: Fri, 1 Jul 2022 21:02:06 +0000 (-0600)
Subject: lib/rand: improve __fill_random_buf()
X-Git-Tag: test-tag-2022-08-09~22
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=aa75fc9db6b98ad317911b35b4a968139a648bb8;p=fio.git

lib/rand: improve __fill_random_buf()

This won't be equivalent to what we have, but I _think_ the randomness
is good enough for this purpose.

This improves performance by about 30% for me, tested on both aarch64
and x86-64.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/lib/rand.c b/lib/rand.c
index 2243c2b4..1df1a7a0 100644
--- a/lib/rand.c
+++ b/lib/rand.c
@@ -103,8 +103,7 @@ void __fill_random_buf(void *buf, unsigned int len, uint64_t seed)
 
 	for (; b != e; ++b) {
 		*b = seed;
-		seed *= GOLDEN_RATIO_PRIME;
-		seed >>= 3;
+		seed *= GOLDEN_RATIO_64;
 	}
 
 	if (fio_unlikely(rest))