On 2014-04-04 21:24, Jens Axboe wrote:
On Fri, Apr 04 2014, Carl Zwanzig wrote:
Hello,
This has been bugging me for a while... it appears that we have a
choice of using either cmd line parameters xor a job file (but not
combining the two) to fully specify a job.
For instance:
fio --runtime=20 derf.cfg
fio: time_based requires a runtime/timeout setting
file__0: (g=0): rw=read, bs=4K-4K/4K-4K/4K-4K, ioengine=libaio, iodepth=32
fio-2.1.6.1
[...]
where derf.cfg starts otherwise fully specified the job, just doesn't
have the runtime.
There are ways around this for some cases by using environment
variables (e.g. "RT=20 fio def.cfg" and runtime=${RT}) but those can
get clunky and only allows value substitutions, not additional
directives. In my current case, I'd like to have the config file
supply default values for certain parameters and override them as
needed from the command line (e.g. runtime=20 unless I say otherwise).
Right now, I already have 6 or 7 env vars passed in to the job file
and that's too many.
Is there any way to do this without really hacking up the parsing
code? I'm currently looking at init.c, where it looks like the cmd
line is parsed first then the job file(s), but I lose the mental
thread when I get into parse_jobs_ini(). Ideally, any fio options on
the command line before a --name= would be stuck at the end of the
global thread data (*td_parent?), similar to including a directive
multiple times.
Should be fairly easy to fix - right now the transition would imply a
job barrier, which is why it doesn't work. We could just assume [global]
state for that.
Took a quick look. The code basically looks like this:
job_files = parse_cmd_line(argc, argv, type);
if (job_files > 0) {
for (i = 0; i < job_files; i++) {
if (fill_def_thread())
[...]
(init.c:2019)
So fio does parse the command line options, and unless they are
sectioned and form a job, they basically go into the default thread
options and hence are considered as part of the [global] section for the
next job file. If you comment out that fill_def_thread() part, it should
work.
It becomes more complicated if you expect this to work:
fio --some_option=1 jobfile.fio --some_other_option=2 jobfile2.fio
which I'd be surprised if that works.
Fio clears the default options between each job file, since they are
considered independent, instead of leaking set [global] option between
job files. That part should remain. But it would be nice to make any
previous command line options be part of the next job file. The full fix
will be larger than just commenting out those two lines, but it should
not be a lot of work.
--
Jens Axboe
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