Re: [PATCH v13 04/10] accel/tcg: add jit stats and time to TBStatistics

[Alex Bennée]

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

> On 5/30/2023 6:08 PM, Alex Bennée wrote:
>> 
>> "Wu, Fei" <fei2.wu@intel.com> writes:
>> 
>>> On 5/30/2023 1:01 PM, Wu, Fei wrote:
>>>> On 5/30/2023 12:07 PM, Richard Henderson wrote:
>>>>> On 5/29/23 04:49, Fei Wu wrote:
<snip>
> ----------------
> IN:
> Priv: 1; Virt: 0
>
> 0xffffffff800abe14:  864a              mv                      a2,s2
> 0xffffffff800abe16:  85ce              mv                      a1,s3
> 0xffffffff800abe18:  8526              mv                      a0,s1
> 0xffffffff800abe1a:  46bd              addi                    a3,zero,15
> 0xffffffff800abe1c:  fffff097          auipc                   ra,-4096
>               # 0xffffffff800aae1c
> 0xffffffff800abe20:  cc0080e7          jalr                    ra,ra,-832
> ------------------------------
>
> Look at the tb with phys:0x2abe14, although the first time IR takes
> 75274ns, but in the second command we can see it takes much less time
> (Note IR time is accumulated).
>
> So if the time for the same TB is not consistent, and the deviation
> could be dominated by system events such as memory allocation instead of
> codegen itself (?), I think it's less useful.
>
> Alex, regarding dropping time profile, do you mean remove TB_JIT_TIME
> completely?

I think so - perf would do a better job of separating system events from
the core code as it has better visibility of the whole system. 

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro