On Fri, Jul 24, 2015 at 2:48 PM, Thomas De Schampheleire <[email protected]> wrote: > Hi, > > With Xenomai Mercury (specifically the PSOS skin, but that doesn't > matter for this question), the minimal stack size applied is > PTHREAD_STACK_MIN * 4, even if the caller requested a smaller one. > > On MIPS, and some other architectures, PTHREAD_STACK_MIN is already 128K: > (<glibc>/ports/sysdeps/unix/sysv/linux/mips/nptl/bits/local_lim.h) > > /* Minimum size for a thread. At least two pages with 64k pages. */ > #define PTHREAD_STACK_MIN 131072 > > With Xenomai multiplying this with 4, every thread has half a megabyte > of stack, which is way too much for systems with a large number of > threads. > It is possible to limit this in other ways, by setting 'ulimit -s 128' > for example, but it is a dirty workaround in my opinion. > > What is the real minimum stack requirement for Xenomai? I cannot > imagine that this is in the order of 512K. > > With PTHREAD_STACK_MIN varying so much on different platforms, what > about code like: > > minimum_stacksize = MAX(XENOMAI_STACK_MIN, PTHREAD_STACK_MIN); > > if (stacksize < minimum_stacksize) { > stacksize = minimum_stacksize; > } > > where XENOMAI_STACK_MIN is a value that is not calculated based on > PTHREAD_STACK_MIN? > > With this approach, systems with 16K PTHREAD_STACK_MIN could still get > 64K minimum stack in case the xenomai minimum stack size is 64K, while > not negatively impacting systems that have 128K PTHREAD_STACK_MIN. > > (Note that for systems with 4K/8K pages, the PTHREAD_STACK_MIN of 128K > (two 'pages' taken for 64K) is already very exaggerated) >
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