Re: [Qemu-devel] [RFC PATCH 0/2] port network layer onto glib

[Anthony Liguori <anthony@codemonkey.ws>]

"Michael S. Tsirkin" <mst@redhat.com> writes:

> On Wed, Mar 13, 2013 at 06:31:57PM +0100, Paolo Bonzini wrote:
>> > We could do that purely
>> > with AioContexts as well, but that rules out a large class of
>> > backends that offloaded event loops can interact with, such as Chardevs,
>> > so I think modelling how to handle both will provide a threading model
>> > that scales better with other devices/subsystems.
>> 
>> .. but I think the "no magic" argument applies here too.  After all we
>> only have a handful of subsystems.  If chardevs are not performance
>> critical, they can keep running in the main thread.
>> 
>> If one day we find out that we need a real-time serial port, and glib
>> just doesn't cut it, we shouldn't be ashamed of ripping GIOChannels out,
>> hand-writing the same stuff, and using a dedicated AioContext.  Of
>> course by the time we get there we'll have unit tests/qtests to make
>> sure we do not regress.  Right??? :)
>> 
>> Paolo
>
> Since you mention serial port, just wanted to say that while it's
> bandwidth requirements are not high, we do need to improve its latency.
> ATM whenever someone tries to use the emulated serial, guest experiences
> stalls and worst case latency jumps, and it's a pain point for many
> users.

Can you be more specific?  I'm not familiar with this issue.

Regards,

Anthony Liguori

>
> -- 
> MST