[dmd-internals] Giving better static data limits to the GC

[Leandro Lucarella]

Walter Bright, el 22 de agosto a las 15:11 me escribiste:
>    Leandro Lucarella wrote:
> 
>  Walter Bright, el 22 de agosto a las 12:25 me escribiste:
> 
> 
>   I know this is probably really low priority for DMD, but any answer
>   would be appreciated, even if it is something like "no idea how doable
>   it is, it would take time to think about it and is low priority" :)
> 
> 
>     I don't think spending a lot of effort on the static data is worthwhile,
>     as very little of modern programs should consist of static mutable data.
> 
>     What's held me back from adding in precise scanning data for everything is
>     the large expansion of the memory footprint of a program to hold all this
>     data.
> 
> 
>  Thanks for the answer. My experiments show that static data is relevant.
>  Comparing 2 GC implementations, one with very few types (druntime
>  implementation) and another using a few more types, including a couple
>  of templates, the second is measurably slower. The types generates
>  a *lot* of rw static data.
> 
>  Even when I agree that it might be too much to add type information to
>  the static data, grouping only the static data that should be scanned
>  (i.e. D-only global variables, and leaving out all the
>  TypeInfo/ClassInfo) can make a big difference.
> 
>  Would that be too hard?
> 
> 
>    I can look into grouping it, but be aware I've had a lot of problems with
>    various linkers trying to get the grouping to work. The Mac linker in
>    particular behaves very unreliably and buggily with this, and its behavior
>    changes erratically with each new OSX release. I'd worry about it not
>    working correctly and the resulting app randomly crashing.

I will be willing to try it out in Linux if you do. Even a really ugly
hack just to make some test would be very useful for me, so I can
confirm or discard that the big static data is what is causing the
problem.

Thanks.


-- 
Leandro Lucarella (AKA luca)                     http://llucax.com.ar/
----------------------------------------------------------------------
GPG Key: 5F5A8D05 (F8CD F9A7 BF00 5431 4145  104C 949E BFB6 5F5A 8D05)
----------------------------------------------------------------------
ASALTAN, GOLPEAN SALVAJEMENTE A ANCIANA Y LE COMEN LA PASTAFROLA.
	-- Crónica TV