As we explore stacking traces, it is nice to be able to scale a trace to
understand how the traces end up interacting.
This patch adds scaling by letting the user pass in percentages to scale
a trace by. When passed '--merge_blktrace_scalars="100", the trace is
ran at 100% speed. If passed 50%, this will halve the trace timestamps.
The new option takes in a comma separated list that index-wise pairs
with the passed files in "--read_iolog".
Signed-off-by: Dennis Zhou <dennis@xxxxxxxxxx>
---
blktrace.c | 35 +++++++++++++++++++++++++++++++++++
blktrace.h | 1 +
options.c | 10 ++++++++++
thread_options.h | 1 +
4 files changed, 47 insertions(+)
diff --git a/blktrace.c b/blktrace.c
index 9cdbd3ca..14acc699 100644
--- a/blktrace.c
+++ b/blktrace.c
@@ -4,6 +4,7 @@
#include <stdio.h>
#include <stdlib.h>
#include <sys/ioctl.h>
+#include <unistd.h>
#include <linux/fs.h>
#include "flist.h"
@@ -614,6 +615,28 @@ err:
return false;
}
+static int init_merge_param_list(fio_fp64_t *vals, struct blktrace_cursor *bcs,
+ int nr_logs, int def, size_t off)
+{
+ int i = 0, len = 0;
+
+ while (len < FIO_IO_U_LIST_MAX_LEN && vals[len].u.f != 0.0)
+ len++;
+
+ if (len && len != nr_logs)
+ return len;
+
+ for (i = 0; i < nr_logs; i++) {
+ int *val = (int *)((char *)&bcs[i] + off);
+ *val = def;
+ if (len)
+ *val = (int)vals[i].u.f;
+ }
+
+ return 0;
+
+}
+
static int find_earliest_io(struct blktrace_cursor *bcs, int nr_logs)
{
__u64 time = ~(__u64)0;
@@ -674,6 +697,8 @@ read_skip:
goto read_skip;
}
+ t->time = t->time * bc->scalar / 100;
+
return ret;
}
@@ -694,6 +719,15 @@ int merge_blktrace_iologs(struct thread_data *td)
char *str, *ptr, *name, *merge_buf;
int i, ret;
+ ret = init_merge_param_list(td->o.merge_blktrace_scalars, bcs, nr_logs,
+ 100, offsetof(struct blktrace_cursor,
+ scalar));
+ if (ret) {
+ log_err("fio: merge_blktrace_scalars(%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);
@@ -765,6 +799,7 @@ err_file:
err_out_file:
fflush(merge_fp);
fclose(merge_fp);
+err_param:
free(bcs);
return ret;
diff --git a/blktrace.h b/blktrace.h
index 1b2bb76b..cebd54d6 100644
--- a/blktrace.h
+++ b/blktrace.h
@@ -11,6 +11,7 @@ struct blktrace_cursor {
int fd; // blktrace file
struct blk_io_trace t; // current io trace
int swap; // bitwise reverse required
+ int scalar; // scale percentage
};
bool is_blktrace(const char *, int *);
diff --git a/options.c b/options.c
index c0deffcb..706f98fd 100644
--- a/options.c
+++ b/options.c
@@ -3207,6 +3207,16 @@ struct fio_option fio_options[FIO_MAX_OPTS] = {
.category = FIO_OPT_C_IO,
.group = FIO_OPT_G_IOLOG,
},
+ {
+ .name = "merge_blktrace_scalars",
+ .lname = "Percentage to scale each trace",
+ .type = FIO_OPT_FLOAT_LIST,
+ .off1 = offsetof(struct thread_options, merge_blktrace_scalars),
+ .maxlen = FIO_IO_U_LIST_MAX_LEN,
+ .help = "Percentage to scale each 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 99552326..9eb6d53e 100644
--- a/thread_options.h
+++ b/thread_options.h
@@ -259,6 +259,7 @@ struct thread_options {
bool read_iolog_chunked;
char *write_iolog_file;
char *merge_blktrace_file;
+ fio_fp64_t merge_blktrace_scalars[FIO_IO_U_LIST_MAX_LEN];
unsigned int write_bw_log;
unsigned int write_lat_log;
--
2.17.1
