On 2011-08-31 14:34, Brian Fallik wrote:
> Hi,
>
> Hmm. I'm still unable to generate random test data using fio. My
> new job control file is:
> [foo0]
> rate =,200k
> rw =write
> refill_buffers =1
> size =4m
>
> [foo1]
> rate =,200k
> rw =write
> refill_buffers =1
> size =4m
> But:
> $ diff foo0.1.0 foo1.2.0
> reports they're identical. I also tried enabling data verification by
> adding "verify=crc32c-intel" but that had no effect. Am I missing
> something obvious or is this potentially broken in fio 1.57?
It's random, just not across jobs apparently... Ooops. The below patch
should rectify that. It's also committed, jfyi.
> I also have another (maybe related?) question. Apologies if this
> belongs in a separate thread, but are there any notes explaining why
> fio lays out the files before starting sequential writes? The
> workload I was hoping to simulate is sustained, sequential writes to
> disk. I'm trying to answer the question "How many simultaneous
> 200kBps writers can we support?" Using my current jobs file, fio
> starts by creating the files (e.g "foo0: Laying out IO file(s) (1
> file(s) / 4MB)") before it starts processing. However, creating the
> files in advance accounts for a chunk of performance that doesn't seem
> to be measured by fio. Am I misunderstanding how to configure fio or
> its intended usage?
You should be able to set overwrite=0 to avoid that. Are they random
writes?
commit 3545a109a2cfe5ab22969ef453dc049db47f0b68
Author: Jens Axboe <jaxboe@xxxxxxxxxxxx>
Date: Wed Aug 31 15:20:15 2011 -0600
Ensure that buffer contents are random across jobs as well
Signed-off-by: Jens Axboe <jaxboe@xxxxxxxxxxxx>
diff --git a/fio.c b/fio.c
index 9c1bed3..4514840 100644
--- a/fio.c
+++ b/fio.c
@@ -874,9 +874,9 @@ static int init_io_u(struct thread_data *td)
io_u->buf = p + max_bs * i;
dprint(FD_MEM, "io_u %p, mem %p\n", io_u, io_u->buf);
- if (td_write(td) && !td->o.refill_buffers)
+ if (td_write(td))
io_u_fill_buffer(td, io_u, max_bs);
- else if (td_write(td) && td->o.verify_pattern_bytes) {
+ if (td_write(td) && td->o.verify_pattern_bytes) {
/*
* Fill the buffer with the pattern if we are
* going to be doing writes.
@@ -1699,7 +1699,6 @@ int main(int argc, char *argv[], char *envp[])
arch_init(envp);
sinit();
- init_rand(&__fio_rand_state);
/*
* We need locale for number printing, if it isn't set then just
diff --git a/fio.h b/fio.h
index 8401eda..6eb270d 100644
--- a/fio.h
+++ b/fio.h
@@ -460,7 +460,7 @@ struct thread_data {
char *sysfs_root;
- unsigned long rand_seeds[7];
+ unsigned long rand_seeds[8];
union {
os_random_state_t bsrange_state;
@@ -475,6 +475,8 @@ struct thread_data {
struct frand_state __trim_state;
};
+ struct frand_state buf_state;
+
unsigned int verify_batch;
unsigned int trim_batch;
diff --git a/init.c b/init.c
index a920c6e..ed34269 100644
--- a/init.c
+++ b/init.c
@@ -515,6 +515,8 @@ void td_fill_rand_seeds(struct thread_data *td)
td_fill_rand_seeds_os(td);
else
td_fill_rand_seeds_internal(td);
+
+ init_rand_seed(&td->buf_state, td->rand_seeds[7]);
}
/*
diff --git a/io_u.c b/io_u.c
index 16c98b1..a87c58e 100644
--- a/io_u.c
+++ b/io_u.c
@@ -1450,7 +1450,7 @@ void io_u_fill_buffer(struct thread_data *td, struct io_u *io_u,
io_u->buf_filled_len = 0;
if (!td->o.zero_buffers)
- fill_random_buf(io_u->buf, max_bs);
+ fill_random_buf(&td->buf_state, io_u->buf, max_bs);
else
memset(io_u->buf, 0, max_bs);
}
diff --git a/lib/rand.c b/lib/rand.c
index 3b2d67a..7c6fed1 100644
--- a/lib/rand.c
+++ b/lib/rand.c
@@ -36,8 +36,6 @@
#include "rand.h"
#include "../hash.h"
-struct frand_state __fio_rand_state;
-
static inline int __seed(unsigned int x, unsigned int m)
{
return (x < m) ? x + m : x;
@@ -79,12 +77,13 @@ void __fill_random_buf(void *buf, unsigned int len, unsigned long seed)
}
}
-unsigned long fill_random_buf(void *buf, unsigned int len)
+unsigned long fill_random_buf(struct frand_state *fs, void *buf,
+ unsigned int len)
{
- unsigned long r = __rand(&__fio_rand_state);
+ unsigned long r = __rand(fs);
if (sizeof(int) != sizeof(long *))
- r *= (unsigned long) __rand(&__fio_rand_state);
+ r *= (unsigned long) __rand(fs);
__fill_random_buf(buf, len, r);
return r;
diff --git a/lib/rand.h b/lib/rand.h
index f80c111..6b9e13c 100644
--- a/lib/rand.h
+++ b/lib/rand.h
@@ -7,8 +7,6 @@ struct frand_state {
unsigned int s1, s2, s3;
};
-extern struct frand_state __fio_rand_state;
-
static inline unsigned int __rand(struct frand_state *state)
{
#define TAUSWORTHE(s,a,b,c,d) ((s&c)<<d) ^ (((s <<a) ^ s)>>b)
@@ -23,6 +21,6 @@ static inline unsigned int __rand(struct frand_state *state)
extern void init_rand(struct frand_state *);
extern void init_rand_seed(struct frand_state *, unsigned int seed);
extern void __fill_random_buf(void *buf, unsigned int len, unsigned long seed);
-extern unsigned long fill_random_buf(void *buf, unsigned int len);
+extern unsigned long fill_random_buf(struct frand_state *, void *buf, unsigned int len);
#endif
diff --git a/verify.c b/verify.c
index fc207cf..c450e88 100644
--- a/verify.c
+++ b/verify.c
@@ -36,7 +36,7 @@ void fill_pattern(struct thread_data *td, void *p, unsigned int len, struct io_u
if (use_seed)
__fill_random_buf(p, len, seed);
else
- io_u->rand_seed = fill_random_buf(p, len);
+ io_u->rand_seed = fill_random_buf(&td->buf_state, p, len);
break;
case 1:
/*
--
Jens Axboe
--
To unsubscribe from this list: send the line "unsubscribe fio" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
