On Mon, Aug 15, 2022 at 02:46:04PM -0700, Andres Freund wrote: > Hi, > > On 2022-08-15 17:39:08 -0400, Michael S. Tsirkin wrote: > > On Mon, Aug 15, 2022 at 02:28:39PM -0700, Andres Freund wrote: > > > On 2022-08-15 17:04:10 -0400, Michael S. Tsirkin wrote: > > > > So virtio has a queue_size register. When read, it will give you > > > > originally the maximum queue size. Normally we just read it and > > > > use it as queue size. > > > > > > > > However, when queue memory allocation fails, and unconditionally with a > > > > network device with the problematic patch, driver is asking the > > > > hypervisor to make the ring smaller by writing a smaller value into this > > > > register. > > > > > > > > I suspect that what happens is hypervisor still uses the original value > > > > somewhere. > > > > > > It looks more like the host is never told about the changed size for legacy > > > devices... > > > > > > Indeed, adding a vp_legacy_set_queue_size() & call to it to setup_vq(), makes > > > 5.19 + restricting queue sizes to 1024 boot again. > > > > Interesting, the register is RO in the legacy interface. > > And to be frank I can't find where is vp_legacy_set_queue_size > > even implemented. It's midnight here too ... > > Yea, I meant that added both vp_legacy_set_queue_size() and a call to it. I > was just quickly experimenting around. interesting that it's writeable on GCP. It's RO on QEMU. > > > Yes I figured this out too. And I was able to reproduce on qemu now. > > Cool. > > > > I'm posting a new patchset reverting all the handing of resize > > restrictions, I think we should rethink it for the next release. > > Makes sense. > > Greetings, > > Andres Freund _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
