Re: [Qemu-devel] [PATCH] AIO: Reduce number of threads for 32bit hosts

[Kevin Wolf]

Am 14.01.2015 um 08:37 hat Paolo Bonzini geschrieben:
> 
> 
> On 14/01/2015 01:56, Alexander Graf wrote:
> > +    if (sizeof(pool) == 4) {
> > +        /* 32bit systems run out of virtual memory quickly */
> > +        pool->max_threads = 4;
> > +    } else {
> > +        pool->max_threads = 64;
> > +    }
> 
> Reviewed-by: Paolo Bonzini <address@hidden>
> 
> The same problem applies to coroutine stacks, and those cannot be
> throttled down as easily.  But I guess if you limit the number of
> threads, the guest gets slowed down and doesn't create as many coroutines.

Shouldn't we rather try and decrease the stack sizes a bit? 1 MB per
coroutine is really a lot, and as I understand it, threads take even
more by default.

> It would be nice to have a way to measure coroutine stack usage, similar
> to what the kernel does.

The information which pages are mapped should be there somewhere...

Kevin