> Are you saying allocateMightFail ignores the usual nursery size?
Right, so normally in Cmm you'd do something like `if (Hp + size > HpLim) {
trigger GC }`, but allocateMightFail adds more blocks to the nursery instead.
Maybe just look at the code, it's quite simple.
I don't know how to check Hp in the RTS and trigger a GC. I'd do that part in
Cmm as there are lots of Cmm functions that do this already (in PrimOps.cmm
and maybe elsewhere).
Ömer
David Feuer <david.fe...@gmail.com>, 20 Eyl 2018 Per, 12:50 tarihinde
şunu yazdı:
>
> I'm not sure I understand. Are you saying allocateMightFail ignores the usual
> nursery size? That's not my intention. It would actually be just fine to
> simply fail if GC would be required--I can then back off, fail out to CMM,
> trigger a GC there, and retry. Or I could perform an extra heap check before
> I start; that's a little silly, but I doubt it'll be expensive enough to
> really matter here.
>
> On Thu, Sep 20, 2018, 5:42 AM Ömer Sinan Ağacan <omeraga...@gmail.com> wrote:
>>
>> 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 <david.fe...@gmail.com>, 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 <omeraga...@gmail.com>
>> > wrote:
>> >>
>> >> 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 <david.fe...@gmail.com>, 20 Eyl 2018 Per, 12:26 tarihinde
>> >> şunu yazdı:
>> >> >
>> >> > 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 <omeraga...@gmail.com>
>> >> > wrote:
>> >> >>
>> >> >> Have you seen Storage.c:allocateMightFail ?
>> >> >>
>> >> >> Ömer
>> >> >>
>> >> >>
>> >> >> David Feuer <david.fe...@gmail.com>, 20 Eyl 2018 Per, 11:32 tarihinde
>> >> >> şunu yazdı:
>> >> >> >
>> >> >> > 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
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