Re: [Qemu-devel] [PATCH] main-loop: Don't lock starve io-threads when main_loop_tlg has pending events

[Alex Bligh]

On 9 Oct 2013, at 15:37, Paolo Bonzini wrote:

> 
> I agree.  Do you also agree that the equivalent workaround, before
> Alex's patch, was MIN_REARM_TIMER_NS (and thus 250 microseconds)?

I don't think this was the case, as if it's a timer constantly
expiring we'd have seen select() exit as soon as it was entered
by the fd poked by the signal. That might be far more frequent.
I think the equivalent would be something like: if the 'zero'
timeout comes from the deadline calculation (and not
nonblocking=true) then release the lock anyway. I think
that would be a reasonable approach.

I would however like to get to the bottom of what's causing
this as even pre my changes playing sound was apparently taking
50% CPU, which is not good. I am completely packed until the
weekend but I propose producing a timer debug patch which
will instrument what is expiring constantly (unless the
problem with spice is obvious to someone).

-- 
Alex Bligh