Alternate GCs

[Jonathan "Duke" Leto]

Howdy,

A while ago we talked about allowing GC's to be chosen at compile time.
Wouldn't that alleviate this pain whilst still allowing GC's to be
pluggable?

Duke

On Mon, Sep 12, 2011 at 7:59 AM, Nicholas Clark <nick at ccl4.org> wrote:
> On Mon, Sep 12, 2011 at 10:42:17AM -0400, Andrew Whitworth wrote:
>
>> Is anybody out there using or relying on the alternate GCs besides
>> GMS? I think I want to rip the older ones out. Right now, because GCs
>> are pluggable, we have to go through an indirect function call for
>> every single GC API call, and the C optimizer can't really do anything
>> with that. I want to rip out the alternate GC cores and flatten some
>> of the call graphs, to give the C compiler some opportunities to
>> optimize the hot paths. I will put together a branch soon, but I want
>> to double-check nobody relies on the old GC cores for any purpose.
>>
>> The idea of pluggable GCs is great in theory, but right now we only
>
> The idea of pluggable GCs is great in theory, but I can't see how it can
> be done (in practice, in a statically compiled language such as C) without
> needing a function call at every single *possible* GC API call. That is,
> a call is needed at any point where the union of the implementations of
> supported GCs need it, even if it's a no-op for the currently chosen GC.
> (Such as a call needed for actions for a write barrier, which always has
> to be made, because a runtime pluggable system can't inline the test for
> whether an invariant has become breached, or remove it entirely for a GC
> that doesn't need write barriers.)
>
> I think compile time flexibility should possible without runtime pain.
> But no flexibility is cheaper to maintain.
>
> Nicholas Clark
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>



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Jonathan "Duke" Leto <jonathan at leto.net>
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