Re: [Qemu-devel] [PATCH 1/2] accel: allows to select the "best" accelerator

[Michael S. Tsirkin]

On Tue, Oct 04, 2016 at 07:16:49PM +0200, Paolo Bonzini wrote:
> 
> 
> On 04/10/2016 16:18, Thomas Huth wrote:
> >>> >> Using only tcg has also some disadvantages: For some tests, it's
> >>> >> interesting to know whether they also work properly with KVM (e.g.
> >>> >> migration tests), and only using tcg by default slows down the "make
> >>> >> check" quite a bit - which might become an issue now that we're adding
> >>> >> more and more tests.
> >> > 
> >> > Which tests are you seeing a slow-down for ?
> > Well, everything that is using accel=tcg in tests/ could be accelerated.
> > For example, the new ipv6/ppc64 unit test is quite slow with TCG:
> > 
> > sudo QTEST_QEMU_BINARY=ppc64-softmmu/qemu-system-ppc64 time tests/pxe-test
> > 
> >  48.46user 0.07system 0:48.48elapsed
> 
> Could that point to a firmware bug?  10 network-bound seconds for a boot
> makes some sense, but 10 CPU-bound seconds don't...
> 
> Paolo

AFAIK pxe firmware typically can't handle interrupts
so it polls for packets.

-- 
MST