From 5973cafb37fbf24c3ca2cdf86a3d03f1b00d6d2b Mon Sep 17 00:00:00 2001
From: Jens Axboe <jens.axboe@oracle.com>
Date: Wed, 21 May 2008 19:52:35 +0200
Subject: [PATCH] Add option for refilling IO buffers on each submit

If the device looks at whether the data changed, then this can
make a difference.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---
 HOWTO     |  5 +++++
 fio.c     | 20 ++------------------
 fio.h     |  2 ++
 io_u.c    | 21 +++++++++++++++++++++
 options.c |  6 ++++++
 5 files changed, 36 insertions(+), 18 deletions(-)

diff --git a/HOWTO b/HOWTO
index 32e7322c..36e42aaf 100644
--- a/HOWTO
+++ b/HOWTO
@@ -336,6 +336,11 @@ bs_unaligned	If this option is given, any byte size value within bsrange
 zero_buffers	If this option is given, fio will init the IO buffers to
 		all zeroes. The default is to fill them with random data.
 
+refill_buffers	If this option is given, fio will refill the IO buffers
+		on every submit. The default is to only fill it at init
+		time and reuse that data. Only makes sense if zero_buffers
+		isn't specified, naturally.
+
 nrfiles=int	Number of files to use for this job. Defaults to 1.
 
 openfiles=int	Number of files to keep open at the same time. Defaults to
diff --git a/fio.c b/fio.c
index b79aa93e..c79fad87 100644
--- a/fio.c
+++ b/fio.c
@@ -642,22 +642,6 @@ static void cleanup_io_u(struct thread_data *td)
 	free_io_mem(td);
 }
 
-/*
- * "randomly" fill the buffer contents
- */
-static void fill_io_buf(struct thread_data *td, struct io_u *io_u, int max_bs)
-{
-	long *ptr = io_u->buf;
-
-	if (!td->o.zero_buffers) {
-		while ((void *) ptr - io_u->buf < max_bs) {
-			*ptr = rand() * GOLDEN_RATIO_PRIME;
-			ptr++;
-		}
-	} else
-		memset(ptr, 0, max_bs);
-}
-
 static int init_io_u(struct thread_data *td)
 {
 	struct io_u *io_u;
@@ -700,8 +684,8 @@ static int init_io_u(struct thread_data *td)
 		if (!(td->io_ops->flags & FIO_NOIO)) {
 			io_u->buf = p + max_bs * i;
 
-			if (td_write(td))
-				fill_io_buf(td, io_u, max_bs);
+			if (td_write(td) && !td->o.refill_buffers)
+				io_u_fill_buffer(td, io_u, max_bs);
 		}
 
 		io_u->index = i;
diff --git a/fio.h b/fio.h
index 47b6d488..25d05bdc 100644
--- a/fio.h
+++ b/fio.h
@@ -478,6 +478,7 @@ struct thread_options {
 	unsigned int group_reporting;
 	unsigned int fadvise_hint;
 	unsigned int zero_buffers;
+	unsigned int refill_buffers;
 	unsigned int time_based;
 
 	char *read_iolog_file;
@@ -907,6 +908,7 @@ extern void io_u_log_error(struct thread_data *, struct io_u *);
 extern void io_u_init_timeout(void);
 extern void io_u_set_timeout(struct thread_data *);
 extern void io_u_mark_depth(struct thread_data *, unsigned int);
+extern void io_u_fill_buffer(struct thread_data *td, struct io_u *, unsigned int);
 
 /*
  * io engine entry points
diff --git a/io_u.c b/io_u.c
index 92cdd717..06fb3cef 100644
--- a/io_u.c
+++ b/io_u.c
@@ -6,6 +6,7 @@
 #include <assert.h>
 
 #include "fio.h"
+#include "hash.h"
 
 /*
  * Change this define to play with the timeout handling
@@ -780,6 +781,9 @@ struct io_u *get_io_u(struct thread_data *td)
 	io_u->endpos = io_u->offset + io_u->buflen;
 	io_u->xfer_buf = io_u->buf;
 	io_u->xfer_buflen = io_u->buflen;
+
+	if (td->o.refill_buffers && io_u->ddir == DDIR_WRITE)
+		io_u_fill_buffer(td, io_u, io_u->xfer_buflen);
 out:
 	if (!td_io_prep(td, io_u)) {
 		fio_gettime(&io_u->start_time, NULL);
@@ -943,6 +947,23 @@ void io_u_queued(struct thread_data *td, struct io_u *io_u)
 	add_slat_sample(td, io_u->ddir, slat_time);
 }
 
+/*
+ * "randomly" fill the buffer contents
+ */
+void io_u_fill_buffer(struct thread_data *td, struct io_u *io_u,
+		      unsigned int max_bs)
+{
+	long *ptr = io_u->buf;
+
+	if (!td->o.zero_buffers) {
+		while ((void *) ptr - io_u->buf < max_bs) {
+			*ptr = rand() * GOLDEN_RATIO_PRIME;
+			ptr++;
+		}
+	} else
+		memset(ptr, 0, max_bs);
+}
+
 #ifdef FIO_USE_TIMEOUT
 void io_u_set_timeout(struct thread_data *td)
 {
diff --git a/options.c b/options.c
index 8a6a4338..ba57e446 100644
--- a/options.c
+++ b/options.c
@@ -1215,6 +1215,12 @@ static struct fio_option options[] = {
 		.off1	= td_var_offset(zero_buffers),
 		.help	= "Init IO buffers to all zeroes",
 	},
+	{
+		.name	= "refill_buffers",
+		.type	= FIO_OPT_STR_SET,
+		.off1	= td_var_offset(refill_buffers),
+		.help	= "Refill IO buffers on every IO submit",
+	},
 #ifdef FIO_HAVE_DISK_UTIL
 	{
 		.name	= "disk_util",
-- 
2.25.1