Re: Heap allocation in the RTS

allocateMightFail allocates new nursery blocks as long as you don't hit the heap limit, so it returns NULL less often than you might think. In particular, it doesn't return NULL when the nursery is full, instead it allocates a new block and adds it to the nursery. I'd do the GC triggering part in Cmm code instead of C code -- I'm not sure if it's possible to do this in C code. There should be some functions in PrimOps.cmm that do heap allocation, maybe look there. I'd look for uses of ALLOC_PRIM. The file HeapStackCheck.cmm may also be helpful (may at least give an idea of how a GC is triggered). Ömer David Feuer , 20 Eyl 2018 Per, 12:34 tarihinde şunu yazdı:

If it returns NULL, then I need to back off what I'm doing and trigger a GC. How do I do the latter?

On Thu, Sep 20, 2018, 5:31 AM Ömer Sinan Ağacan wrote:

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allocateMightFail does the heap check for you and returns NULL. For the current capability you can use MyCapability() in Cmm and pass the value to the RTS function you're implementing.

Ömer

David Feuer , 20 Eyl 2018 Per, 12:26 tarihinde şunu yazdı:

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Aha! Okay. How do I get the current capability to pass to that? I guess I should probably perform a heap check before calling lookupSta bleName for simplicity, at least to start.

On Thu, Sep 20, 2018, 5:16 AM Ömer Sinan Ağacan wrote:

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Have you seen Storage.c:allocateMightFail ?

Ömer

David Feuer , 20 Eyl 2018 Per, 11:32 tarihinde şunu yazdı:

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I'm working on re-implementing the stable name system. For the new design, it seems much cleaner to allocate stable names in lookupStableName (in rts/StableName.c) rather than in the C-- code that calls it. But I haven't seen RTS code that does heap allocation. Is it possible? If so, how do I do it? _______________________________________________ ghc-devs mailing list ghc-devs@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs