Hi Richard, On Thu, Jan 28, 2016 at 2:37 PM, Richard Plangger <planrichi@gmail.com> wrote:

the file rpython/translator/c/src/stack.h defines MAX_STACK_SIZE. PPC has a bigger limit than e.g. x86. I experienced that on s390x there is as well a higher consumption of memory for stack frames (they are variable sized with a pretty high minimum limit (160 bytes) by the ABI).

I have two questions:

1) The OS (i.e. linux) defines a stack limit (ulimit -s), does pypy overwrite this value with MAX_STACK_SIZE?

2) How would I determine which size is best for s390x? Or how did we come up with 768kb for x86, and 2.8mb for ppc?

The stack limit is some number that is choosen to correspond to a bit more than 1000 recursive levels of a typical Python program when run by PyPy without JIT, as compiled with a typical "gcc -O3". It's thus very much hand-waving. The limit of 768 KB was done in this way. It's much lower than the stack provided by the OS, so no "ulimit" is needed. I had to pick a higher limit for PPC because 768 KB was definitely too low there. Likely, you should measure more precisely how many levels you get on x86-64 (I think it was around 1400) and pick a value for s390x that gives a similar limit. A bientôt, Armin.

Hi Richard, On Thu, Jan 28, 2016 at 2:37 PM, Richard Plangger <planrichi@gmail.com> wrote:

the file rpython/translator/c/src/stack.h defines MAX_STACK_SIZE. PPC has a bigger limit than e.g. x86. I experienced that on s390x there is as well a higher consumption of memory for stack frames (they are variable sized with a pretty high minimum limit (160 bytes) by the ABI).

I have two questions:

1) The OS (i.e. linux) defines a stack limit (ulimit -s), does pypy overwrite this value with MAX_STACK_SIZE?

2) How would I determine which size is best for s390x? Or how did we come up with 768kb for x86, and 2.8mb for ppc?

The stack limit is some number that is choosen to correspond to a bit more than 1000 recursive levels of a typical Python program when run by PyPy without JIT, as compiled with a typical "gcc -O3". It's thus very much hand-waving. The limit of 768 KB was done in this way. It's much lower than the stack provided by the OS, so no "ulimit" is needed. I had to pick a higher limit for PPC because 768 KB was definitely too low there. Likely, you should measure more precisely how many levels you get on x86-64 (I think it was around 1400) and pick a value for s390x that gives a similar limit. A bientôt, Armin.