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

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Date:   Tue, 11 Feb 2020 14:47:04 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     John Garry <john.garry@...wei.com>
Cc:     peterz@...radead.org, mingo@...hat.com, acme@...nel.org,
        mark.rutland@....com, alexander.shishkin@...ux.intel.com,
        namhyung@...nel.org, will@...nel.org, ak@...ux.intel.com,
        linuxarm@...wei.com, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, suzuki.poulose@....com,
        james.clark@....com, zhangshaokun@...ilicon.com,
        robin.murphy@....com
Subject: Re: [PATCH RFC 5/7] perf pmu: Support matching by sysid

On Mon, Feb 10, 2020 at 04:22:56PM +0000, John Garry wrote:
> 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@huawei.com/
> 
> 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/

I'll try to check ;-)

> 
> > > +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?

I wish to see some test for all this.. I can only think about having
'test' json files compiled with perf and 'perf test' that looks them
up and checks that all is in the proper place

jirka