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Re: PPC needs lots more stack space in rawhide??



David Woodhouse <dwmw2 infradead org> writes:
> On Wed, 2008-01-09 at 11:11 -0500, Tom Lane wrote:
>> Interesting, but would that affect the rate at which userland code
>> consumes stack space?

> It'll certainly affect the way it _allocates_ stack space.

>> Since posting, I've verified that it still fails at STACK_MIN_SIZE = 48K,

> That's still less than a single page. Did you try 64KiB or 128KiB?

I think you're missing the context.  The actual requested size of the
thread stack is 192K or 256K (and I've also tried 512K, without any
better luck).  I could see kernel page size affecting the result of that
allocation request, but all the values are multiples of 64K already.

The problem I'm having is with some code that tries to detect how much
stack space has been consumed, and error out if it's too much, where
"too much" means the requested stack size minus STACK_MIN_SIZE.  So that
constant needs to be set large enough to ensure that the error recovery
code itself can execute without overflowing the stack and incurring
SIGSEGV.

My first assumption was that something was using a tad more stack space
than before, but given the latest failed test I'm starting to think that
something's been broken about the stack-depth-testing logic itself.

			regards, tom lane


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