Re: [PATCH v1 8/9] plugins: new hwprofile plugin

[Robert Foley]

On Wed, 3 Jun 2020 at 07:43, Alex Bennée <alex.bennee@linaro.org> wrote:
>
>
> Robert Foley <robert.foley@linaro.org> writes:
>
<snip>
> >
> > When testing out the options, I noticed that
> > if we supply arguments of "read", and "write", then we will only get
> > the last one set, "write", since rw gets overwritten.
> > One option would be to error out if more than one of these read/write
> > args is supplied.
>
> Yeah the option parsing is a little clunky although given the way you
> pass them from the QEMU command line perhaps not too worth finessing.
> The default is rw so you make a conscious decision to only care about one
> or the other.
>
> All you can really do is fail to initialise the plugin. Hopefully the
> output should be enough clue.
>
> >
> > Reviewed-by: Robert Foley <robert.foley@linaro.org>
> > Tested-by: Robert Foley <robert.foley@linaro.org>
>
> Thanks.
>
> Out of interest what did you measure? Are there any useful use cases you can
> think of?

We did some testing where we booted an aarch64 VM and an i386 VM a few times
with differentcore counts (up to 64), and viewed the counters.  We
also did a test where
we inserted another device (a virtfs mount), booted up and checked
that there was another
device listed (for virtio-9p).

There are a few useful use cases we are thinking of, in general for debug/perf
 testing of PCI devices/drivers.
For example, debug and performance test of a case where we use a queue pair,
(maybe for something like DPDK/SPDK), this plugin would be interesting for
checking that the quantity and locations of accesses are expected.

Thanks & Regards,
-Rob
>
> >
> >> +            detail = true;
> >> +        } else {
> >> +            fprintf(stderr, "option parsing failed: %s\n", opt);
> >> +            return -1;
> >> +        }
> >> +    }
> >> +
> >> +    plugin_init();
> >> +
> >> +    qemu_plugin_register_vcpu_tb_trans_cb(id, vcpu_tb_trans);
> >> +    qemu_plugin_register_atexit_cb(id, plugin_exit, NULL);
> >> +    return 0;
> >> +}
> >> diff --git a/tests/plugin/Makefile b/tests/plugin/Makefile
> >> index b3250e2504c..d87b8d40699 100644
> >> --- a/tests/plugin/Makefile
> >> +++ b/tests/plugin/Makefile
> >> @@ -14,6 +14,7 @@ NAMES += hotblocks
> >>  NAMES += howvec
> >>  NAMES += hotpages
> >>  NAMES += lockstep
> >> +NAMES += hwprofile
> >>
> >>  SONAMES := $(addsuffix .so,$(addprefix lib,$(NAMES)))
> >>
> >> --
> >> 2.20.1
> >>
>
>
> --
> Alex Bennée