Hi all,
because I got bitten by this multiple times I decided to give this patch
a try :)
Current implementation of offset calculation when offset_increment is in
effect uses global thread_number as follows:
f->file_offset = td->o.start_offset + (td->thread_number - 1) *
td->o.offset_increment;
The thread number gets incremented for every job (subjob) so even you
have multiple jobs with different filenames, the offset calculation is
shared. I find this very unintuitive, especially in cases the offsets
gets past the device/file. For example, if one wants to run sequential
read test in 16 threads of multiple devices (/dev/sd{b,c,d}) in one
group, which are of 1TB size, and to eliminate caching effect he wants
each read to start at different offset, the config could look like
following:
[seq-read-16threads-/dev/sdb]
rw=read
numjobs=16
offset_increment=50g
bs=512k
filename=/dev/sdb
[seq-read-16threads-/dev/sdc]
rw=read
numjobs=16
offset_increment=50g
bs=512k
filename=/dev/sdc
[seq-read-16threads-/dev/sdd]
rw=read
numjobs=16
offset_increment=50g
bs=512k
filename=/dev/sdd
The result will be that only /dev/sdb is full tested, three threads will
be run against /dev/sdc and /dev/sdd does not receive any IO at all.
The proposed patch add new option "reset_offset_increment" that causes
the offset calculation to be started again from zero. The idea behind is
similar to patch proposed here
(http://www.spinics.net/lists/fio/msg01213.html) but is more flexible.
The patch applies against 2.1.9 tag.
Regards
Jiri Horky
diff -Nru fio-2.1.9/filesetup.c fio-2.1.9.patched/filesetup.c
--- fio-2.1.9/filesetup.c 2014-05-20 09:39:25.000000000 +0200
+++ fio-2.1.9.patched/filesetup.c 2014-05-23 13:22:31.069984999 +0200
@@ -750,7 +750,7 @@
return f->real_file_size;
return td->o.start_offset +
- (td->thread_number - 1) * td->o.offset_increment;
+ (td->offset_thread_number - 1) * td->o.offset_increment;
}
/*
diff -Nru fio-2.1.9/fio.1 fio-2.1.9.patched/fio.1
--- fio-2.1.9/fio.1 2014-05-20 09:39:25.000000000 +0200
+++ fio-2.1.9.patched/fio.1 2014-05-23 13:40:02.154049921 +0200
@@ -647,10 +647,19 @@
.TP
.BI offset_increment \fR=\fPint
If this is provided, then the real offset becomes the
-offset + offset_increment * thread_number, where the thread number is a counter
-that starts at 0 and is incremented for each job. This option is useful if
-there are several jobs which are intended to operate on a file in parallel in
-disjoint segments, with even spacing between the starting points.
+offset + offset_increment * offset_thread_number, where the offset thread number is a
+counter that starts at 0 and is incremented for each job unless reset_offset_increment
+is specified. This option is useful if there are several jobs which are intended to
+operate on a file in parallel in disjoint segments, with even spacing between the
+starting points.
+.TP
+.BI reset_offset_increment \fR=\fPbool
+By default, fio uses global thread numbers when computing offset with offset_increment.
+This may be often confusing as different jobs/threads may operate on different files
+but still share the same offset_increment. This option resets the offset_thread_number
+to 0. If your jobs operate on different files, use this option for every file
+to get offset_increment-per-file behavior. If you use subjobs (numbjobs=X), the
+reset will be done only once before the first subjob starts.
.TP
.BI number_ios \fR=\fPint
Fio will normally perform IOs until it has exhausted the size of the region
diff -Nru fio-2.1.9/fio.h fio-2.1.9.patched/fio.h
--- fio-2.1.9/fio.h 2014-05-20 09:39:07.000000000 +0200
+++ fio-2.1.9.patched/fio.h 2014-05-23 12:57:43.263971178 +0200
@@ -101,6 +101,7 @@
char verror[FIO_VERROR_SIZE];
pthread_t thread;
unsigned int thread_number;
+ unsigned int offset_thread_number;
unsigned int groupid;
struct thread_stat ts;
diff -Nru fio-2.1.9/init.c fio-2.1.9.patched/init.c
--- fio-2.1.9/init.c 2014-05-20 09:39:07.000000000 +0200
+++ fio-2.1.9.patched/init.c 2014-05-23 13:26:00.969989815 +0200
@@ -43,6 +43,7 @@
static struct thread_data def_thread;
struct thread_data *threads = NULL;
+static int offset_thread_number = 0;
static char **job_sections;
static int nr_job_sections;
@@ -1116,6 +1117,11 @@
groupid++;
}
+ if (o->reset_offset_increment) {
+ offset_thread_number = 0;
+ }
+
+ td->offset_thread_number = ++offset_thread_number;
td->groupid = groupid;
prev_group_jobs++;
@@ -1198,6 +1204,7 @@
td_new->o.numjobs = 1;
td_new->o.stonewall = 0;
td_new->o.new_group = 0;
+ td_new->o.reset_offset_increment = 0;
if (file_alloced) {
if (td_new->files) {
diff -Nru fio-2.1.9/options.c fio-2.1.9.patched/options.c
--- fio-2.1.9/options.c 2014-05-20 09:39:25.000000000 +0200
+++ fio-2.1.9.patched/options.c 2014-05-23 13:00:24.929232053 +0200
@@ -1669,6 +1669,18 @@
.group = FIO_OPT_G_INVALID,
},
{
+ .name = "reset_offset_increment",
+ .lname = "Reset offset increment counter",
+ .type = FIO_OPT_STR_VAL,
+ .off1 = td_var_offset(reset_offset_increment),
+ .help = "Resets increment counter to 0",
+ .parent = "offset",
+ .hide = 1,
+ .def = "0",
+ .category = FIO_OPT_C_IO,
+ .group = FIO_OPT_G_INVALID,
+ },
+ {
.name = "number_ios",
.lname = "Number of IOs to perform",
.type = FIO_OPT_STR_VAL,
diff -Nru fio-2.1.9/thread_options.h fio-2.1.9.patched/thread_options.h
--- fio-2.1.9/thread_options.h 2014-05-20 09:39:07.000000000 +0200
+++ fio-2.1.9.patched/thread_options.h 2014-05-23 12:58:38.012721048 +0200
@@ -247,6 +247,7 @@
unsigned int flow_sleep;
unsigned long long offset_increment;
+ unsigned int reset_offset_increment;
unsigned long long number_ios;
unsigned int sync_file_range;
