linux-kernel - Re: [RFC PATCH 2/5] perf jevents: add support for arch recommended events

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Date:   Wed, 3 Jan 2018 12:22:16 +0000
From:   John Garry <john.garry@...wei.com>
To:     Andi Kleen <ak@...ux.intel.com>
CC:     Jiri Olsa <jolsa@...hat.com>, <peterz@...radead.org>,
        <mingo@...hat.com>, <acme@...nel.org>,
        <alexander.shishkin@...ux.intel.com>, <namhyung@...nel.org>,
        <wcohen@...hat.com>, <will.deacon@....com>,
        <ganapatrao.kulkarni@...ium.com>, <catalin.marinas@....com>,
        <mark.rutland@....com>, <xuwei5@...ilicon.com>,
        <linuxarm@...wei.com>, <zhangshaokun@...ilicon.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 2/5] perf jevents: add support for arch recommended
 events

On 02/01/2018 17:48, Andi Kleen wrote:
>> Can you describe how you autogenerate the JSONs? Do you have some internal
>> proprietary HW file format describing events, with files supplied from HW
>> designer, which you can just translate into a JSON? Would the files support
>> deferencing events to improve scalability?
>
> For Intel JSON is an official format, which is maintained for each CPU.
> It is automatically generated from an internal database
> https://download.01.org/perfmon/
>
> I have some python scripts to convert these Intel JSONs into the perf
> format (which has some additional headers, and is split into
> different categories, and add metrics).

OK, understood.

Unfortunately I could not see such a database being maintained for ARM 
implementors.

>
> They have some Intel specifics, so may not be useful for you.
>
> There's no support for dereference, each CPU gets its own unique file.

Right.

>
> But you could do the a merge simply with the attached script which merges
> two JSON files.

I assume that you're talking about simply merging the micro architecture 
and the platform specific event JSONS at build time.

If yes, this would not work for us:
- the microarchitecture JSON would contain definitions of all events, 
but there is no architectural method to check if they are implemented
- we need to deal with scenario of non-standard event implementations

But I could update the script to deal with this and add to the build 
(Jirka looked to be ok with the same in jevents, albeit a few caveats).

All the best,
John

>
> -Andi
>