abnormally high load?

[Mark Moseley]

On Wed, Aug 12, 2009 at 7:06 PM, Ken Brownfield<kb+varnish at slide.com> wrote:
> I never found a way to see how much stack is /used/ vs. /allocated/ in
> a process or thread, so it would be great if someone had ideas?
>
> I could only experiment in production, first moving us to 1MB, then
> 256KB.  I've yet to see any issues at 256KB, but we can reach the
> upper limits of thread-count sanity on our boxes with that setting, so
> I haven't dropped it further in production.
>
> The minimums I reached in minimal testing were 128KB with the ulimit
> method, and 64KB with the (IMHO cleaner) backend/worker-thread-only
> approach.  I'm not sure what in Varnish would use more than that much
> stack, but 256KB seems like the sweet spot.
>
> We're 64-bit Ubuntu, and I would assume that a somewhat smaller stack
> would work on 32-bit, possibly making 128KB safe.
>
> Unless you're doing recursion or using large declared structures in
> inline C, I wouldn't think you'd see large stack allocations or huge
> shifts in allocation during operation.  I don't /believe/ objects are
> ever allocated on the stack, or that there's a lot of recursion in the
> code.
>
> FWIW I personally don't see any red flags.
> --
> Ken

That's excellent information. We're still very early in our varnish
deployment, so tuning info is greatly appreciated. Thanks!