From 71cf4d08b2250c11e11fb1ae49e97e70fbeb322e Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Fri, 7 Jul 2017 08:37:49 -0600 Subject: [PATCH] init: add comment as to how we seed read/write/trim generators Signed-off-by: Jens Axboe --- init.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/init.c b/init.c index 1f1ceebf..9b2b63d6 100644 --- a/init.c +++ b/init.c @@ -921,6 +921,12 @@ static void td_fill_rand_seeds_internal(struct thread_data *td, bool use64) { int i; + /* + * trimwrite is special in that we need to generate the same + * offsets to get the "write after trim" effect. If we are + * using bssplit to set buffer length distributions, ensure that + * we seed the trim and write generators identically. + */ if (td_trimwrite(td)) { init_rand_seed(&td->bsrange_state[DDIR_READ], td->rand_seeds[FIO_RAND_BS_OFF], use64); init_rand_seed(&td->bsrange_state[DDIR_WRITE], td->rand_seeds[FIO_RAND_BS1_OFF], use64); -- 2.25.1