Re: [Qemu-devel] Qemu and heavily increased RSS usage

[Peter Maydell]

On 24 June 2016 at 10:37, Stefan Hajnoczi <address@hidden> wrote:
> On Wed, Jun 22, 2016 at 09:56:06PM +0100, Peter Maydell wrote:
>> On 22 June 2016 at 20:55, Peter Lieven <address@hidden> wrote:
>> > What makes the coroutine pool memory intensive is the stack size of 1MB per
>> > coroutine. Is it really necessary to have such a big stack?
>>
>> That reminds me that I was wondering if we should allocate
>> our coroutine stacks with MAP_GROWSDOWN (though if we're
>> not actually using 1MB of stack then it's only going to
>> be eating virtual memory, not necessarily real memory.)
>
> Yes, MAP_GROWSDOWN will not reduce RSS.

Right, but then the 1MB of stack as currently allocated isn't
going to be affecting RSS either I would have thought (except
transiently, since we zero it on allocation which will
bring it into the RSS until it falls back out again
because we don't touch it after that).

thanks
-- PMM