Re: [Qemu-devel] [PULL 22/26] target/aarch64: optimize indirect branches

[Richard Henderson]

On 06/07/2017 07:11 AM, Alex Bennée wrote:
> Richard Henderson <address@hidden> writes:
>
> > From: "Emilio G. Cota" <address@hidden>
> >
> > Measurements:
> >
> > [Baseline performance is that before applying this and the previous
> > commit]
>
> Sadly this has regressed my qemu-system-aarch64 EL2 run. It was slightly
> masked by an unrelated assertion breakage which I had to fix. However
> with this patch my boot hangs spinning all 4 threads. Once reverted
> things work again.
>
> My command line:
>
>    timeout -k 1s --foreground 120s ./aarch64-softmmu/qemu-system-aarch64 -machine 
> type=virt -display none -m 4096 -cpu cortex-a57 -serial mon:stdio -netdev user,id=unet 
> -device virtio-net-device,netdev=unet -drive 
> file=/home/alex/lsrc/qemu/images/jessie-arm64.qcow2,id=myblock,index=0,if=none -device 
> virtio-blk-device,drive=myblock -append "console=ttyAMA0 root=/dev/vda1 
> systemd.unit=benchmark.service" -kernel 
> /home/alex/lsrc/qemu/images/aarch64-current-linux-kernel-only.img -smp 4 -machine 
> gic-version=3 -machine virtualization=true -name debug-threads=on

If you ignore the timeout, does it complete eventually?

It may not be the same thing, but that pull left out the final patch for 
target/alpha that enabled goto_ptr.  But as I hadn't seen a similar problem 
with other guests, I was assuming that the problem was in hw/alpha/, or some 
other bit of the interrupt chain.


r~