On Mon, Dec 9, 2019 at 9:31 PM Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
>
[ ... ]
> > diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
> > index 49730d6..e7fb1bd 100644
> > --- a/tracecmd/trace-record.c
> > +++ b/tracecmd/trace-record.c
> > @@ -5405,6 +5405,8 @@ static void parse_record_options(int argc,
> > char *sav;
> > int name_counter = 0;
> > int neg_event = 0;
> > + struct buffer_instance *instance;
> > + bool guest_config = false;
>
> Should have a different name, like "clock_set", as "guest_config"
> doesn't let us know what this is about.
I use the same flag in patch 16 from the same series, with the same purpose -
to apply host config to the guest. That's why decided to call it "guest_config".
>
>
> >
> > init_common_record_context(ctx, curr_cmd);
> >
> > @@ -5562,6 +5564,7 @@ static void parse_record_options(int argc,
> > break;
> > case 'C':
> > ctx->instance->ftrace->clock = optarg;
> > + guest_config = true;
> > break;
> > case 'v':
> > neg_event = 1;
> > @@ -5779,14 +5782,26 @@ static void parse_record_options(int argc,
> >
> > /* If --date is specified, prepend it to all guest VM flags */
> > if (ctx->date) {
> > - struct buffer_instance *instance;
> > -
> > for_all_instances(instance) {
> > if (is_guest(instance))
> > add_argv(instance, "--date", true);
> > }
> > }
> >
> > + if (guest_config) {
> > + /* If -C is specified, prepend clock to all guest VM flags */
> > + for_all_instances(instance) {
> > + if (top_instance.ftrace->clock) {
> > + if (is_guest(instance)) {
>
> We should only append this, if the guest didn't have a clock set
> already. As the change log seems to say, if the user states a "-C
> clock" for the guest, that should take precedence over the host clock
> set. That is, a user may specifically state that they are using a
> different clock. If we have frequency and offset set, it should still
> work with different clocks.
The guest config string is not parsed in the host context, that's why the host
doesn't know if a guest has an explicit "-C clock" argument.
I can parse the guest config here, but this will complicate the implementation.
Using the current approach still guarantees that the user specified
config has higher
priority than injected one - add_argv() API prepends to the beginning
of the string, so
user arguments are always after the injected one. When guest parses
the string, in case of
duplicated "-C clock" arguments, the last one wins.
>
> -- Steve
>
>
> > + add_argv(instance,
> > + (char *)top_instance.ftrace->clock,
> > + true);
> > + add_argv(instance, "-C", true);
> > + }
> > + }
> > + }
> > + }
> > +
> > if (!ctx->filtered && ctx->instance->filter_mod)
> > add_func(&ctx->instance->filter_funcs,
> > ctx->instance->filter_mod, "*");
>
Thanks !
--
Tzvetomir (Ceco) Stoyanov
VMware Open Source Technology Center
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