Re: [Qemu-block] virtio-scsi and request splitting

[Peter Lieven]

Am 01.06.2017 um 16:21 schrieb Paolo Bonzini:
> On 01/06/2017 16:11, Peter Lieven wrote:
> > Where shall I send the traces?
> >
> > The output for the dd phase looks sth like this. Is this correct?
> >
> > virtqueue_alloc_element 30498.707 pid=28286 elem=0x560dcca24200 sz=0xf0 
> > in_num=0x1 out_num=0x36
> > virtqueue_alloc_element 7.558 pid=28286 elem=0x560dcca22680 sz=0xf0 in_num=0x1 
> > out_num=0x1a
> > virtqueue_alloc_element 1.410 pid=28286 elem=0x560dcdf916c0 sz=0xf0 in_num=0x1 
> > out_num=0x2
> Yeah, I guess this is enough.  This is it:
>
>      DEFINE_PROP_UINT32("max_sectors", VirtIOSCSI,
>                         parent_obj.conf.max_sectors,
>                         0xFFFF),
>
> We could increase it now that we have support for max_xfer_len passthrough.

0xFFFF * 512 is 32MB - 512 byte. This should not limit 1M requests?!

blockdev --getmaxsect /dev/sda reports 1024 though. However, for virtio-blk its
also 1024, but here 1M requests work.

Peter