linux-kernel - Re: [PATCH v2 7/7] perf test: Test pmu-events aliases

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Date:   Fri, 20 Mar 2020 09:24:19 +0000
From:   John Garry <john.garry@...wei.com>
To:     Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>,
        Jiri Olsa <jolsa@...hat.com>
CC:     <peterz@...radead.org>, <mingo@...hat.com>, <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>, <james.clark@....com>,
        <qiangqing.zhang@....com>
Subject: Re: [PATCH v2 7/7] perf test: Test pmu-events aliases

On 19/03/2020 18:36, Arnaldo Carvalho de Melo wrote:
> Em Tue, Mar 17, 2020 at 06:07:30PM +0100, Jiri Olsa escreveu:
>> On Tue, Mar 17, 2020 at 04:41:04PM +0000, John Garry wrote:
>>> On 17/03/2020 16:20, Jiri Olsa wrote:
>>>> On Tue, Mar 17, 2020 at 07:02:19PM +0800, John Garry wrote:
>>>>> @@ -36,6 +51,8 @@ static struct perf_pmu_test_event test_cpu_events[] = {
>>>>>    			.desc = "Number of segment register loads",
>>>>>    			.topic = "other",
>>>>>    		},
>>>>> +		.alias_str = "umask=0x80,(null)=0x30d40,event=0x6",
> 
>>>> ah so we are using other pmus because of the format definitions
> 
>>>> why is there the '(null)' in there?
> 
>>> Well this is just coming from the generated alias string in the pmu code,
>>> and it does not seem to be handling "period" argument properly. It needs to
>>> be checked.
>   
>> nice, it found first issue already ;-)

thanks

> 
> Applied the series to perf/core, good job! What about the fix for the
> above (null) problem?

So I had started to look at that, but then the codepath lead into the 
lex parsing, which I am not familiar with.

So from when we parse the event terms in parse_events_terms(), we get 3x 
terms:
config=umask, then newval=umask=0x80
confg=(null), then newval=umask=0x80,(null)=x030d40
config=event, then newval=umask=0x80,(null)=x030d40,event=0x6

I can continue to look. Maybe jirka has an idea on this and what happens 
in the lex parsing.

Cheers,
John