Re: [PATCH RFC 5/7] perf pmu: Support matching by sysid

[John Garry]

Hi jirka,

> > +		fclose(file);
> > +		pr_debug("gets failed for file %s\n", path);
> > +		free(buf);
> > +		return NULL;
> > +	}
> > +	fclose(file);
> > +
> > +	/* Remove any whitespace, this could be from ACPI HID */
> > +	s = strlen(buf);
> > +	for (i = 0; i < s; i++) {
> > +		if (buf[i] == ' ') {
> > +			buf[i] = 0;
> > +			break;
> > +		};
> > +	}
> > +
> > +	return buf;
> > +}
> > +

I have another series to add kernel support for a system identifier 
sysfs entry, which I sent after this series:

https://lore.kernel.org/linux-acpi/1580210059-199540-1-git-send-email-john.garry@xxxxxxxxxx/

It is different to what I am relying on here - it uses a kernel soc 
driver for firmware ACPI PPTT identifier. Progress is somewhat blocked 
at the moment however and I may have to use a different method:

https://lore.kernel.org/linux-acpi/20200128123415.GB36168@bogus/

> > +static char *perf_pmu__getsysid(void)
> > +{
> > +	char *sysid;
> > +	static bool printed;
> > +
> > +	sysid = getenv("PERF_SYSID");
> > +	if (sysid)
> > +		sysid = strdup(sysid);
> > +
> > +	if (!sysid)
> > +		sysid = get_sysid_str();
> > +	if (!sysid)
> > +		return NULL;
> > +
> > +	if (!printed) {
> > +		pr_debug("Using SYSID %s\n", sysid);
> > +		printed = true;
> > +	}
> > +	return sysid;
> > +}
>
> this part is getting complicated and AFAIK we have no tests for it
>
> if you could think of any tests that'd be great.. Perhaps we could
> load 'our' json test files and check appropriate events/aliasses
> via in pmu object.. or via parse_events interface.. those test aliases
> would have to be part of perf, but we have tests compiled in anyway

Sorry, I don't fully follow.

Are you suggesting that we could load the specific JSONs tables for a 
system from the host filesystem?

Thanks,
John