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

[Wu, Fei]

On 4/17/2023 9:01 PM, Wu, Fei wrote:
> On 4/17/2023 8:11 PM, Alex Bennée wrote:
>>
>> "Wu, Fei" <fei2.wu@intel.com> writes:
>>
>>> On 4/11/2023 3:27 PM, Alex Bennée wrote:
>>>>
>>>> "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.
>>>>
>>> I have rebased the patches to upstream here:
>>>     https://github.com/atwufei/qemu/tree/tbstats
>>>
>>> I try to keep the patches as possible as they are, but there are lots of
>>> changes since then, so changes are inevitable, e.g. CF_NOCACHE has been
>>> removed from upstream, I just removed its usage in the corresponding
>>> patch, which might not be preferred.
>>
>> Yeah that fine. CF_NOCACHE was removed to avoid special cases in the
>> generation code - we simply don't link or store the TBs in the QHT
>> anymore. As long as the guest isn't executing a lot of non-RAM code we
>> won't run out of translation buffer too quickly.
>>
>>>
>>> I did some basic tests and they worked (the output of info goes to qemu
>>> console, instead of telnet terminal), including:
>>>     * tb_stats start
>>>     * info tb-list
>>>     * info tb 10
>>>
>>> Alex, would you please take a look?
>>
>> That looks pretty good, glad it wasn't too painful a re-base.
>>
>> The next question is do you want to pick up the series and put through a
>> review cycle or two to get merged? It would probably be worth checking
>> the last posting thread to see if their are any outstanding review
>> comments.
>>
> Yes, I can do it. I have something else in hand right now, so the review
> request may be sent out in a few days.
> 
I have sent the review out here, hope you have received it:
   https://www.mail-archive.com/qemu-devel@nongnu.org/msg955889.html

I just received the cover letter w/o the following patches, I do
subscribe to qemu-devel@nongnu.org, not sure why.

Thanks,
Fei.


> Thanks,
> Fei.