On Fri, Aug 11, 2023 at 5:21 PM Michael S. Tsirkin <mst@xxxxxxxxxx> wrote: > > On Fri, Aug 11, 2023 at 05:18:51PM +0800, Jason Wang wrote: > > On Fri, Aug 11, 2023 at 1:42 PM Michael S. Tsirkin <mst@xxxxxxxxxx> wrote: > > > > > > On Fri, Aug 11, 2023 at 10:23:15AM +0800, Jason Wang wrote: > > > > On Fri, Aug 11, 2023 at 3:41 AM Michael S. Tsirkin <mst@xxxxxxxxxx> wrote: > > > > > > > > > > On Tue, Aug 08, 2023 at 10:30:56AM +0800, Jason Wang wrote: > > > > > > On Mon, Jul 31, 2023 at 2:30 PM Jason Wang <jasowang@xxxxxxxxxx> wrote: > > > > > > > > > > > > > > On Thu, Jul 27, 2023 at 5:46 PM Michael S. Tsirkin <mst@xxxxxxxxxx> wrote: > > > > > > > > > > > > > > > > On Thu, Jul 27, 2023 at 04:59:33PM +0800, Jason Wang wrote: > > > > > > > > > > They really shouldn't - any NIC that takes forever to > > > > > > > > > > program will create issues in the networking stack. > > > > > > > > > > > > > > > > > > Unfortunately, it's not rare as the device/cvq could be implemented > > > > > > > > > via firmware or software. > > > > > > > > > > > > > > > > Currently that mean one either has sane firmware with a scheduler that > > > > > > > > can meet deadlines, or loses ability to report errors back. > > > > > > > > > > > > > > > > > > But if they do they can always set this flag too. > > > > > > > > > > > > > > > > > > This may have false negatives and may confuse the management. > > > > > > > > > > > > > > > > > > Maybe we can extend the networking core to allow some device specific > > > > > > > > > configurations to be done with device specific lock without rtnl. For > > > > > > > > > example, split the set_channels to > > > > > > > > > > > > > > > > > > pre_set_channels > > > > > > > > > set_channels > > > > > > > > > post_set_channels > > > > > > > > > > > > > > > > > > The device specific part could be done in pre and post without a rtnl lock? > > > > > > > > > > > > > > > > > > Thanks > > > > > > > > > > > > > > > > > > > > > > > > Would the benefit be that errors can be reported to userspace then? > > > > > > > > Then maybe. I think you will have to show how this works for at least > > > > > > > > one card besides virtio. > > > > > > > > > > > > > > Even for virtio, this seems not easy, as e.g the > > > > > > > virtnet_send_command() and netif_set_real_num_tx_queues() need to > > > > > > > appear to be atomic to the networking core. > > > > > > > > > > > > > > I wonder if we can re-consider the way of a timeout here and choose a > > > > > > > sane value as a start. > > > > > > > > > > > > Michael, any more input on this? > > > > > > > > > > > > Thanks > > > > > > > > > > I think this is just mission creep. We are trying to fix > > > > > vduse - let's do that for starters. > > > > > > > > > > Recovering from firmware timeouts is far from trivial and > > > > > just assuming that just because it timed out it will not > > > > > access memory is just as likely to cause memory corruption > > > > > with worse results than an infinite spin. > > > > > > > > Yes, this might require support not only in the driver > > > > > > > > > > > > > > I propose we fix this for vduse and assume hardware/firmware > > > > > is well behaved. > > > > > > > > One major case is the re-connection, in that case it might take > > > > whatever longer that the kernel virito-net driver expects. > > > > So we can have a timeout in VDUSE and trap CVQ then VDUSE can return > > > > and fail early? > > > > > > Ugh more mission creep. not at all my point. vduse should cache > > > values in the driver, > > > > What do you mean by values here? The cvq command? > > > > Thanks > > The card status generally. Just to make sure I understand here. The CVQ needs to be processed by the userspace now. How could we cache the status? Thanks > > > > until someone manages to change > > > net core to be more friendly to userspace devices. > > > > > > > > > > > > Or maybe not well behaved firmware will > > > > > set the flag losing error reporting ability. > > > > > > > > This might be hard since it means not only the set but also the get is > > > > unreliable. > > > > > > > > Thanks > > > > > > /me shrugs > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Thanks > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > > > MST > > > > > > > > > > > > > > > > > _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
