From: Jens Axboe <jens.axboe@oracle.com>
Date: Thu, 22 Mar 2007 17:56:45 +0000 (+0100)
Subject: Add support for mixing a random IO workload a bit
X-Git-Tag: fio-1.15~48
X-Git-Url: https://git.kernel.dk/?p=fio.git;a=commitdiff_plain;h=211097b2aa664b8c157692a1e2fe656ed4a3488c

Add support for mixing a random IO workload a bit

Now you can append a number to randread/randwrite (and others) to
specify only getting a random offset for every X number of ios.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---

diff --git a/HOWTO b/HOWTO
index 76613714..051a4554 100644
--- a/HOWTO
+++ b/HOWTO
@@ -228,7 +228,14 @@ rw=str		Type of io pattern. Accepted values are:
 
 		For the mixed io types, the default is to split them 50/50.
 		For certain types of io the result may still be skewed a bit,
-		since the speed may be different.
+		since the speed may be different. It is possible to specify
+		a number of IO's to do before getting a new offset - this
+		is only useful for random IO, where fio would normally
+		generate a new random offset for every IO. If you append
+		eg 8 to randread, you would get a new random offset for
+		every 8 IO's. The result would be a seek for only every 8
+		IO's, instead of for every IO. Use rw=randread:8 to specify
+		that.
 
 randrepeat=bool	For random IO workloads, seed the generator in a predictable
 		way so that results are repeatable across repetitions.
diff --git a/fio.h b/fio.h
index e3334908..c34c00c0 100644
--- a/fio.h
+++ b/fio.h
@@ -325,6 +325,7 @@ struct thread_options {
 	char *opendir;
 	char *ioengine;
 	enum td_ddir td_ddir;
+	unsigned int ddir_nr;
 	unsigned int iodepth;
 	unsigned int iodepth_low;
 	unsigned int iodepth_batch;
@@ -503,6 +504,7 @@ struct thread_data {
 	unsigned long long rwmix_bytes;
 	struct timeval rwmix_switch;
 	enum fio_ddir rwmix_ddir;
+	unsigned int ddir_nr;
 
 	/*
 	 * IO historic logs
diff --git a/io_u.c b/io_u.c
index 2b18e9f8..45f37570 100644
--- a/io_u.c
+++ b/io_u.c
@@ -52,7 +52,7 @@ static void mark_random_map(struct thread_data *td, struct io_u *io_u)
 	while (blocks < nr_blocks) {
 		unsigned int idx, bit;
 
-		if (!random_map_free(td, f, block))
+		if (!td->o.ddir_nr && !random_map_free(td, f, block))
 			break;
 
 		idx = RAND_MAP_IDX(td, f, block);
@@ -109,6 +109,16 @@ static int get_next_offset(struct thread_data *td, struct io_u *io_u)
 		unsigned long long max_blocks = f->file_size / td->o.min_bs[ddir];
 		int loops = 5;
 
+		if (td->o.ddir_nr) {
+			if (!td->ddir_nr)
+				td->ddir_nr = td->o.ddir_nr;
+			else if (--td->ddir_nr) {
+				b = f->last_pos / td->o.min_bs[ddir];
+				goto out;
+			} else
+				td->ddir_nr = td->o.ddir_nr;
+		}
+
 		do {
 			r = os_random_long(&td->random_state);
 			if (!max_blocks)
@@ -130,6 +140,7 @@ static int get_next_offset(struct thread_data *td, struct io_u *io_u)
 	} else
 		b = f->last_pos / td->o.min_bs[ddir];
 
+out:
 	io_u->offset = (b * td->o.min_bs[ddir]) + f->file_offset;
 	if (io_u->offset >= f->real_file_size)
 		return 1;
diff --git a/options.c b/options.c
index e13b2b24..41ecd7fd 100644
--- a/options.c
+++ b/options.c
@@ -27,6 +27,20 @@ static char *get_opt_postfix(const char *str)
 	return strdup(p);
 }
 
+static int str_rw_cb(void *data, const char *str)
+{
+	struct thread_data *td = data;
+	char *nr = get_opt_postfix(str);
+
+	td->o.ddir_nr = 0;
+	if (nr)
+		td->o.ddir_nr = atoi(nr);
+
+	printf("ddir_nr=%d\n", td->o.ddir_nr);
+
+	return 0;
+}
+
 static int str_mem_cb(void *data, const char *mem)
 {
 	struct thread_data *td = data;
@@ -203,6 +217,7 @@ static struct fio_option options[] = {
 		.name	= "rw",
 		.alias	= "readwrite",
 		.type	= FIO_OPT_STR,
+		.cb	= str_rw_cb,
 		.off1	= td_var_offset(td_ddir),
 		.help	= "IO direction",
 		.def	= "read",