Poor virtio performance on Scaleway ARM systems

[Greg V]

On Fri, Oct 26, 2018 at 7:34 AM, Peter Jeremy <peter at rulingia.com> 
wrote:
> On 2018-Oct-23 18:46:05 +0300, Greg V <greg at unrelenting.technology> 
> wrote:
>> echo 'hw.pci.honor_msi_blacklist="0"' >> /boot/loader.conf
>> 
>> With the fix, we're getting ~1000 interrupts on 'its0,4: virtio_pci1'
>> (instead of ~30000 on gic), latency is no longer awful, and bandwidth
>> is about 220 MB/s. YAY!!
> 
> Unfortunately, this isn't working for me on 13-CURRENT.  I am still
> seeing ~4.5MBps disk I/O with ~30,000 interrupts/sec on gic0,s5.  I
> don't even see an its0,4.
> 
> Looking at a verbose boot, the relevant errors are:
> 
> its0: <ARM GIC Interrupt Translation Service> mem 0x8080000-0x809ffff 
> on gic0
> its0: GITS_BASER0: unable to be updated: a907000040a40607 != 
> a907000040ee0607
> device_attach: its0 attach returned 6

Yeah, I think I mentioned this above, sometimes its0 fails to attach. 
Just reboot.