Re: How to control the number of random I/O's acrossing the whole file/device?

[Jens Axboe <axboe@kernel.dk>]

On Fri, Aug 09 2013, Jiahua wrote:
> I have a 1TB disk and try to do a fixed number, say 1000, random 4KB
> I/O's cross the whole disk. If I use size=4MB, I can only touch the
> first 4MB range of the disk instead of the whole disk range. If I set
> size as 1TB, it will do much more than 1000 I/O's and run too long. As
> for time_based, it is not ideal since I cannot control the I/O number
> precisely.

Ah, I see what you mean. Try and patch the below in, then set
number_ios=1000 and see if it does what you want.

diff --git a/cconv.c b/cconv.c
index 8e7c69e..21e3a51 100644
--- a/cconv.c
+++ b/cconv.c
@@ -146,6 +146,7 @@ void convert_thread_options_to_cpu(struct thread_options *o,
 	o->zone_skip = le64_to_cpu(top->zone_skip);
 	o->lockmem = le64_to_cpu(top->lockmem);
 	o->offset_increment = le64_to_cpu(top->offset_increment);
+	o->number_ios = le64_to_cpu(top->number_ios);
 
 	o->overwrite = le32_to_cpu(top->overwrite);
 	o->bw_avg_time = le32_to_cpu(top->bw_avg_time);
@@ -394,6 +395,7 @@ void convert_thread_options_to_net(struct thread_options_pack *top,
 	top->start_offset = __cpu_to_le64(o->start_offset);
 	top->trim_backlog = __cpu_to_le64(o->trim_backlog);
 	top->offset_increment = __cpu_to_le64(o->offset_increment);
+	top->number_ios = __cpu_to_le64(o->number_ios);
 
 	for (i = 0; i < FIO_IO_U_LIST_MAX_LEN; i++)
 		top->percentile_list[i].u.i = __cpu_to_le64(fio_double_to_uint64(o->percentile_list[i].u.f));
diff --git a/io_u.c b/io_u.c
index a35aafd..c50a17d 100644
--- a/io_u.c
+++ b/io_u.c
@@ -1413,6 +1413,9 @@ static void account_io_completion(struct thread_data *td, struct io_u *io_u,
 		add_bw_sample(td, idx, bytes, &icd->time);
 
 	add_iops_sample(td, idx, bytes, &icd->time);
+
+	if (td->o.number_ios && !--td->o.number_ios)
+		td->done = 1;
 }
 
 static long long usec_for_io(struct thread_data *td, enum fio_ddir ddir)
diff --git a/options.c b/options.c
index 1816d0b..caf89d3 100644
--- a/options.c
+++ b/options.c
@@ -1483,6 +1483,16 @@ struct fio_option fio_options[FIO_MAX_OPTS] = {
 		.group	= FIO_OPT_G_INVALID,
 	},
 	{
+		.name	= "number_ios",
+		.lname	= "Number of IOs to perform",
+		.type	= FIO_OPT_STR_VAL,
+		.off1	= td_var_offset(number_ios),
+		.help	= "Force job completion of this number of IOs",
+		.def	= "0",
+		.category = FIO_OPT_C_IO,
+		.group	= FIO_OPT_G_INVALID,
+	},
+	{
 		.name	= "bs",
 		.lname	= "Block size",
 		.alias	= "blocksize",
diff --git a/thread_options.h b/thread_options.h
index eaafaee..3f345c5 100644
--- a/thread_options.h
+++ b/thread_options.h
@@ -236,6 +236,7 @@ struct thread_options {
 	unsigned int flow_sleep;
 
 	unsigned long long offset_increment;
+	unsigned long long number_ios;
 
 	unsigned int sync_file_range;
 };
@@ -440,6 +441,7 @@ struct thread_options_pack {
 	uint32_t flow_sleep;
 
 	uint64_t offset_increment;
+	uint64_t number_ios;
 
 	uint32_t sync_file_range;
 } __attribute__((packed));

-- 
Jens Axboe