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/file.h b/file.h
index add77730fdb43931ba2fff38881b9196b3175395..bb303103048cd847e3918efc18c98efbda1950fb 100644 (file)
--- a/file.h
+++ b/file.h
@@ -88,8 +88,11 @@ struct fio_file {
        uint64_t file_offset;
        uint64_t io_size;
 
-       uint64_t last_pos;
-       uint64_t last_start;
+       /*
+        * Track last end and last start of IO for a given data direction
+        */
+       uint64_t last_pos[DDIR_RWDIR_CNT];
+       uint64_t last_start[DDIR_RWDIR_CNT];
 
        uint64_t first_write;
        uint64_t last_write;

diff --git a/filesetup.c b/filesetup.c
index cc6d44091736aeba9e6ba1ab5be7a3d56bc29c1b..a918234fb77f9df22d2e77fb80a40919fdc46df0 100644 (file)
--- a/filesetup.c
+++ b/filesetup.c
@@ -1536,8 +1536,13 @@ void free_release_files(struct thread_data *td)
 
 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)

diff --git a/io_u.c b/io_u.c
index f1359083528600a17185bd06252430514d053a6c..efbcea9eb15bb47dca4e0f802f85ad86197665de 100644 (file)
--- a/io_u.c
+++ b/io_u.c
@@ -249,7 +249,7 @@ static int get_next_rand_block(struct thread_data *td, struct fio_file *f,
        }
 
        dprint(FD_IO, "%s: rand offset failed, last=%llu, size=%llu\n",
-                       f->file_name, (unsigned long long) f->last_pos,
+                       f->file_name, (unsigned long long) f->last_pos[ddir],
                        (unsigned long long) f->real_file_size);
        return 1;
 }
@@ -261,17 +261,17 @@ static int get_next_seq_offset(struct thread_data *td, struct fio_file *f,
 
        assert(ddir_rw(ddir));
 
-       if (f->last_pos >= f->io_size + get_start_offset(td, f) &&
+       if (f->last_pos[ddir] >= f->io_size + get_start_offset(td, f) &&
            o->time_based)
-               f->last_pos = f->last_pos - f->io_size;
+               f->last_pos[ddir] = f->last_pos[ddir] - f->io_size;
 
-       if (f->last_pos < f->real_file_size) {
+       if (f->last_pos[ddir] < f->real_file_size) {
                uint64_t pos;
 
-               if (f->last_pos == f->file_offset && o->ddir_seq_add < 0)
-                       f->last_pos = f->real_file_size;
+               if (f->last_pos[ddir] == f->file_offset && o->ddir_seq_add < 0)
+                       f->last_pos[ddir] = f->real_file_size;
 
-               pos = f->last_pos - f->file_offset;
+               pos = f->last_pos[ddir] - f->file_offset;
                if (pos && o->ddir_seq_add) {
                        pos += o->ddir_seq_add;
 
@@ -330,8 +330,8 @@ static int get_next_block(struct thread_data *td, struct io_u *io_u,
                                *is_random = 0;
                        }
                } else if (td->o.rw_seq == RW_SEQ_IDENT) {
-                       if (f->last_start != -1ULL)
-                               offset = f->last_start - f->file_offset;
+                       if (f->last_start[ddir] != -1ULL)
+                               offset = f->last_start[ddir] - f->file_offset;
                        else
                                offset = 0;
                        ret = 0;
@@ -743,7 +743,7 @@ static int fill_io_u(struct thread_data *td, struct io_u *io_u)
                 */
                if (f->file_offset >= f->real_file_size)
                        f->file_offset = f->real_file_size - f->file_offset;
-               f->last_pos = f->file_offset;
+               f->last_pos[io_u->ddir] = f->file_offset;
                td->io_skip_bytes += td->o.zone_skip;
        }
 
@@ -1471,8 +1471,8 @@ struct io_u *get_io_u(struct thread_data *td)
                        goto err_put;
                }
 
-               f->last_start = io_u->offset;
-               f->last_pos = io_u->offset + io_u->buflen;
+               f->last_start[io_u->ddir] = io_u->offset;
+               f->last_pos[io_u->ddir] = io_u->offset + io_u->buflen;
 
                if (io_u->ddir == DDIR_WRITE) {
                        if (td->flags & TD_F_REFILL_BUFFERS) {