Re: [PATCH 1/2] accel/tcg/plugin: export host insn size

[Alex Bennée]

"Wu, Fei" <fei2.wu@intel.com> writes:

> On 4/10/2023 6:36 PM, Alex Bennée wrote:
>> 
>> Richard Henderson <richard.henderson@linaro.org> writes:
>> 
>>> On 4/6/23 00:46, Alex Bennée wrote:
>>>> If your aim is to examine JIT efficiency what is wrong with the current
>>>> "info jit" that you can access via the HMP? Also I'm wondering if its
>>>> time to remove the #ifdefs from CONFIG_PROFILER because I doubt the
>>>> extra data it collects is that expensive.
>>>> Richard, what do you think?
>>>
>>> What is it that you want from CONFIG_PROFILER that you can't get from perf?
>>> I've been tempted to remove CONFIG_PROFILER entirely.
>> 
>> I think perf is pretty good at getting the hot paths in the translator
>> and pretty much all of the timer related stuff in CONFIG_PROFILER could
>> be dropped. However some of the additional information about TCG ops
>> usage and distribution is useful. That said last time I had a tilt at
>> this on the back of a GSoC project:
>> 
>>   Subject: [PATCH  v9 00/13] TCG code quality tracking and perf integration
>>   Date: Mon,  7 Oct 2019 16:28:26 +0100
>>   Message-Id: <20191007152839.30804-1-alex.bennee@linaro.org>
>> 
>> The series ended up moving all the useful bits of CONFIG_PROFILER into
>> tb stats which was dynamically controlled on a per TB basis. Now that
>> the perf integration stuff was merged maybe there is a simpler series to
>> be picked out of the remains?
>> 
>> Fei Wu,
>> 
>> Have you looked at the above series? Is that gathering the sort of
>> things you need? Is this all in service of examining the translation
>> quality of hot code?
>> 
> Yes, it does have what I want, I suppose this wiki is for the series:
>     https://wiki.qemu.org/Features/TCGCodeQuality

Yes.

>
> btw, the archive seems broken and cannot show the whole series:
>     https://www.mail-archive.com/qemu-devel@nongnu.org/msg650258.html

I have a v10 branch here:

  https://github.com/stsquad/qemu/tree/tcg/tbstats-and-perf-v10

I think the top two patches can be dropped on a re-base as the JIT/perf
integration is already merged. It might be a tricky re-base though.
Depends on how much churn there has been in the tree since.

>
> Thanks,
> Fei.
>
>>>
>>>
>>> r~
>> 
>> 


-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro