Re: [Qemu-devel] [RFC] create a single workqueue for each vm to update vm irq routing table

[Avi Kivity]

On 11/28/2013 01:10 PM, Paolo Bonzini wrote:
> Il 28/11/2013 12:09, Gleb Natapov ha scritto:
> > > - if there are no callbacks, but there are readers, synchronize_srcu
> > > busy-loops for some time checking if the readers complete.  After a
> > > while (20 us for synchronize_srcu, 120 us for
> > > synchronize_srcu_expedited) it gives up and starts using a workqueue to
> > > poll every millisecond.  This should never happen unless
> > Unless what ? :) Unless reader is scheduled out?
> Yes.  Or unless my brain is scheduled out in the middle of a sentence.

You need a grace period.  Or just sleep().