Scaling a particular trace may result in different runtimes among the
merging traces. By knowing the approximate length of each trace as a
user, the overall runtime of each can be tuned to line up by letting
certain traces loop multiple times.
First, the last timestamp of a trace is recorded at the end of the first
iteration to denote the length of a trace. This value is then used to
offset subsequent iterations of a trace.
Next, the "--merge_blktrace_iters" option is introduced to let the user
specify the number of times to loop over each specific trace. This is
done by passing a comma separated list that index-wise pairs with the
passed files in "--read_iolog". Iteration counts are introduced as well
as keeping track of the length of each trace.
In an example, given two traces, A and B, each 60s long. If we want to
see the impact of trace A issuing IOs twice as fast, the
--merge_blktrace_scalars="50,100" can be set and then
--merge_blktrace_iters="2,1". This runs trace A at 2x the speed twice for
approximately the same runtime as a single run of trace B.
Signed-off-by: Dennis Zhou <dennis@xxxxxxxxxx>
---
blktrace.c | 23 +++++++++++++++++++++--
blktrace.h | 5 +++++
options.c | 10 ++++++++++
thread_options.h | 1 +
4 files changed, 37 insertions(+), 2 deletions(-)
diff --git a/blktrace.c b/blktrace.c
index 14acc699..1d33c6a4 100644
--- a/blktrace.c
+++ b/blktrace.c
@@ -654,6 +654,12 @@ static int find_earliest_io(struct blktrace_cursor *bcs, int nr_logs)
static void merge_finish_file(struct blktrace_cursor *bcs, int i, int *nr_logs)
{
+ bcs[i].iter++;
+ if (bcs[i].iter < bcs[i].nr_iter) {
+ lseek(bcs[i].fd, 0, SEEK_SET);
+ return;
+ }
+
*nr_logs -= 1;
/* close file */
@@ -672,7 +678,11 @@ static int read_trace(struct thread_data *td, struct blktrace_cursor *bc)
read_skip:
/* read an io trace */
ret = trace_fifo_get(td, bc->fifo, bc->fd, t, sizeof(*t));
- if (ret <= 0) {
+ if (ret < 0) {
+ return ret;
+ } else if (!ret) {
+ if (!bc->length)
+ bc->length = bc->t.time;
return ret;
} else if (ret < (int) sizeof(*t)) {
log_err("fio: short fifo get\n");
@@ -697,7 +707,7 @@ read_skip:
goto read_skip;
}
- t->time = t->time * bc->scalar / 100;
+ t->time = (t->time + bc->iter * bc->length) * bc->scalar / 100;
return ret;
}
@@ -728,6 +738,15 @@ int merge_blktrace_iologs(struct thread_data *td)
goto err_param;
}
+ ret = init_merge_param_list(td->o.merge_blktrace_iters, bcs, nr_logs,
+ 1, offsetof(struct blktrace_cursor,
+ nr_iter));
+ if (ret) {
+ log_err("fio: merge_blktrace_iters(%d) != nr_logs(%d)\n",
+ ret, nr_logs);
+ goto err_param;
+ }
+
/* setup output file */
merge_fp = fopen(td->o.merge_blktrace_file, "w");
merge_buf = malloc(128 * 1024);
diff --git a/blktrace.h b/blktrace.h
index cebd54d6..72d74cf8 100644
--- a/blktrace.h
+++ b/blktrace.h
@@ -4,14 +4,19 @@
#ifdef FIO_HAVE_BLKTRACE
+#include <asm/types.h>
+
#include "blktrace_api.h"
struct blktrace_cursor {
struct fifo *fifo; // fifo queue for reading
int fd; // blktrace file
+ __u64 length; // length of trace
struct blk_io_trace t; // current io trace
int swap; // bitwise reverse required
int scalar; // scale percentage
+ int iter; // current iteration
+ int nr_iter; // number of iterations to run
};
bool is_blktrace(const char *, int *);
diff --git a/options.c b/options.c
index 706f98fd..9b277309 100644
--- a/options.c
+++ b/options.c
@@ -3217,6 +3217,16 @@ struct fio_option fio_options[FIO_MAX_OPTS] = {
.category = FIO_OPT_C_IO,
.group = FIO_OPT_G_IOLOG,
},
+ {
+ .name = "merge_blktrace_iters",
+ .lname = "Number of iterations to run per trace",
+ .type = FIO_OPT_FLOAT_LIST,
+ .off1 = offsetof(struct thread_options, merge_blktrace_iters),
+ .maxlen = FIO_IO_U_LIST_MAX_LEN,
+ .help = "Number of iterations to run per trace",
+ .category = FIO_OPT_C_IO,
+ .group = FIO_OPT_G_IOLOG,
+ },
{
.name = "exec_prerun",
.lname = "Pre-execute runnable",
diff --git a/thread_options.h b/thread_options.h
index 9eb6d53e..b3c1e06c 100644
--- a/thread_options.h
+++ b/thread_options.h
@@ -260,6 +260,7 @@ struct thread_options {
char *write_iolog_file;
char *merge_blktrace_file;
fio_fp64_t merge_blktrace_scalars[FIO_IO_U_LIST_MAX_LEN];
+ fio_fp64_t merge_blktrace_iters[FIO_IO_U_LIST_MAX_LEN];
unsigned int write_bw_log;
unsigned int write_lat_log;
--
2.17.1
