Fix read/write mix and different levels of randomness
Stephen reports:
When using fio configuration below:
[global]
ioengine=libaio
direct=1
runtime=600
bs=32k
iodepth=8
rw=randrw
rwmixread=80
percentage_random=100,0
[drive1]
filename=/dev/sda
I am expecting to see 80% reads, 20% writes where all reads are random
and all writes are sequential. I captured a bus trace of traffic to the
disk and the bus trace reflected as much with one issue. The write
commands are essentially random. Each write begins at a new random LBA.
If 2 or more writes occur in a row, the LBA's are sequential based on
the block size BUT I feel the heart of this feature would be to emulate
a large file write during random access. With that in mind would it be
possible for sequential reads or writes within mixed sequential/random
workload to remember the last LBA accessed? In this scenario the writes
would still only take up 20% of the workload but when a write did occur
it should be the next sequential step from the last write.
-----
This is due to the fact that fio tracks last start/end on a unified
basis, not per read/write/trim direction. Fix that.
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/filesetup.c b/filesetup.c
index cc6d440..a918234 100644
--- a/filesetup.c
+++ b/filesetup.c
@@ -1536,8 +1536,13 @@
void fio_file_reset(struct thread_data *td, struct fio_file *f)
{
- f->last_pos = f->file_offset;
- f->last_start = -1ULL;
+ int i;
+
+ for (i = 0; i < DDIR_RWDIR_CNT; i++) {
+ f->last_pos[i] = f->file_offset;
+ f->last_start[i] = -1ULL;
+ }
+
if (f->io_axmap)
axmap_reset(f->io_axmap);
if (td->o.random_generator == FIO_RAND_GEN_LFSR)