Re: Follow-on from does Lua need a JIT - making Lua's interpreter faster

[Dibyendu Majumdar <mobile@...>]

Hi Sean,

On 22 February 2017 at 18:57, Sean Conner <sean@conman.org> wrote:
> It was thus said that the Great Dibyendu Majumdar once stated:
>> It seems from the majority of responses so far that JIT is not
>> essential for Lua, or putting it another way, a majority of use cases
>> can be satisfied without a JIT.
>>
>> A natural follow on question is can the interpreter be made faster
>> without resorting to hand-written assembly code or other esoteric
>> optimisations?
>>
>   Profile, profile, profile.
>

I agree that profiling is important. But normal C profiling doesn't
tell you much as it doesn't reveal which Lua bytecodes are important
to optimise. So I have (not released yet) an option in Ravi to measure
time taken by each bytecode and the number of bytecode executions - by
dumping this out once can understand better where to focus.

Second issue with profiling is you need test applications to profile.
This is perhaps the hardest problem - I do not know of representative
pure Lua apps that I could run just to obtain profiling data.

Regards
Dibyendu