On 11 March 2014 at 20:38, David Chisnall <thera...@freebsd.org> wrote:
> On 12 Mar 2014, at 02:07, Roger Pau Monné <roger....@citrix.com> wrote:
>> I've found out that the value PTHREAD_STACK_MIN is currently set (2048
>> bytes) seems to be way too low
> This looks like an error in your code. The spec says:
>> Minimum size in bytes of thread stack storage.
>> Minimum Acceptable Value: 0
> It is meant to be the minimum value that the system can give for a thread
> stack. The purpose of this constant is for languages that do their own stack
> management bit some chain of activation records of segmented stacks, but want
> to use pthreads for threading, so that they can allocate the smallest
> possible stack that allows pthread cleanup to work.
> Using it from C code is very likely to be a mistake.
I found that lang/polyml uses PTHREAD_STACK_MIN for a trivial signal
handler thread it creates. They found it was too small and
implemented a 4K minimum bound to fix polyml on FreeBSD. Even if
this isn't really the intended use of PTHREAD_STACK_MIN it suggests
the 2K x86 minimum may indeed be too low.
I ran into this while trying LLVM's libunwind, which requires more
stack space. 2K is certainly too low with LLVM libunwind. Is it
reasonable to just increase it to say 8K?
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