Token-based flow control
This patch allows two fio jobs to be kept to a certain
proportion of each other using token-based flow control.
There are three new parameters: flow, flow_watermark, and
flow_sleep, documented in the fio options. An example of an fio
job using these parameters is below:
[global]
norandommap
thread
time_based
runtime=30
direct=1
ioengine=libaio
iodepth=256
size=100g
bs=8k
filename=/tmp/testfile
flow_watermark=100
flow_sleep=1000
[job2]
numjobs=1
rw=write
flow=-8
[job1]
numjobs=1
rw=randread
flow=1
The motivating application of this patch was to allow random reads
and sequential writes at a particular given proportion.
This initial version is only correct when run with 'thread', as shared
state is represented with a global variable. It also only allows two
jobs to be synchronized properly. A future version might do more, but
no more functionality was needed for my application.
Tested: Ran a few fio jobs with this flow control, observing
the proportion of IOPS to match what was intended by the job file.
Varied the flow_watermark and flow_sleep parameters and observed
the effect on throughput.
Signed-off-by: Dan Ehrenberg <dehrenberg@google.com>
Modified by me to support flow_id, so an arbitrary number of flows can
be used. This means it no longer relies on global context, so it can be
used from a thread or process alike. Also added man page documentation.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/fio.h b/fio.h
index c462980..5c912d0 100644
--- a/fio.h
+++ b/fio.h
@@ -38,6 +38,7 @@
#include "lib/rand.h"
#include "server.h"
#include "stat.h"
+#include "flow.h"
#ifdef FIO_HAVE_GUASI
#include <guasi.h>
@@ -258,6 +259,11 @@
unsigned int uid;
unsigned int gid;
+ int flow_id;
+ int flow;
+ int flow_watermark;
+ unsigned int flow_sleep;
+
unsigned int sync_file_range;
};
@@ -470,6 +476,8 @@
unsigned int total_err_count;
int first_error;
+ struct fio_flow *flow;
+
/*
* Can be overloaded by profiles
*/