[Vm-dev] Maximum value of -stackpages VM parameter?

Eliot Miranda eliot.miranda at gmail.com
Mon Jun 12 20:42:52 UTC 2017

Hi Phil,

> On Jun 12, 2017, at 12:50 PM, Phil B <pbpublist at gmail.com> wrote:
> In trying to troubleshoot an issue, I needed to bump up the stackpages parameter.  On 64-bit Linux, a value of 600 worked but 1000 segfaulted so I was just wondering what the limit(s) are for it?

There are no explicit limits.  The set fault you're seeing is as a result of the stack pages being allocated on the c stack.  When the number is high the stack overflows and boom.

A word to the wise: too high a value and scavenging performance falls (stack pages are implicitly roots into new space), and become performance falls (all activations in stack space are scanned post become to avoid a read barrier on inst var fetch).

The default value was 192, a value chosen to exceed qwaq server process usage, but both at Cadence and in Spur profiling we found that was not a good value and pulled it back to 64 (IIRC).

I'm curious as to why are you exploring such high values.

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