On Mon, Nov 22, 2021 at 5:08 PM Eli Cohen <e...@nvidia.com> wrote: > > On Mon, Nov 22, 2021 at 04:07:24PM +0800, Jason Wang wrote: > > On Mon, Nov 22, 2021 at 3:56 PM Eli Cohen <e...@nvidia.com> wrote: > > > > > > On Mon, Nov 22, 2021 at 10:30:12AM +0800, Jason Wang wrote: > > > > On Fri, Nov 19, 2021 at 11:09 AM Parav Pandit <pa...@nvidia.com> wrote: > > > > > > > > > > > > > > > > > > > > > From: Jason Wang <jasow...@redhat.com> > > > > > > Sent: Friday, November 19, 2021 8:12 AM > > > > > > > > > > > > On Thu, Nov 18, 2021 at 1:58 PM Eli Cohen <e...@nvidia.com> wrote: > > > > > > > > > > > > > > Add support for querying virtqueue statistics. Supported > > > > > > > statistics are: > > > > > > > > > > > > > > Received_desc - number of descriptors received for the virtqueue > > > > > > > completed_desc - number of descriptors completed for the virtqueue > > > > > > > > > > > > > > A new callback was added to vdpa_config_ops which provides the > > > > > > > means > > > > > > > for the vdpa driver to return statistics results. > > > > > > > > > > > > > > The interface allows for reading all the supported virtqueues, > > > > > > > including the control virtqueue if it exists, by returning the > > > > > > > next > > > > > > > queue index to query. > > > > > > > > > > > > > > Examples: > > > > > > > 1. Read statisitics for the virtqueue at index 1 $ vdpa dev stats > > > > > > > show > > > > > > > vdpa-a index 1 > > > > > > > vdpa-a: > > > > > > > index 1 tx received_desc 21 completed_desc 21 > > > > > > > > > > > > > > 2. Read statisitics for all the virtqueues vdpa dev stats show > > > > > > > vdpa-a > > > > > > > vdpa-a: > > > > > > > index 0 rx received_desc 256 completed_desc 12 index 1 tx > > > > > > > received_desc 21 completed_desc 21 index 2 ctrl received_desc 0 > > > > > > > completed_desc 0 > > > > > > > > > > > > Adding Adrian and Laurent. > > > > > > > > > > > > It's quite useful but I think it's vendor specific statistics. > > > > > These are vdpa device specific of Linux. > > > > > And are very generic of the VQ for all device types. > > > > > > > > The question is what happens if the parent doesn't implement those > > > > statistics. > > > > > > > > > > Are you suggesting that some parents may support reporting a subeset of > > > the fields and we should maybe indicate what is actually reported? > > > > It's an open question. E.g do we want a stable API for the those > > statistics counter? If yes, it's better to not to let the parents to > > report a subset but then it forces the exact same counters to be > > supported by other vendors. If not, it should be fine. For any case, I > > think it's simpler to start with "vendor-stats" and we can switch it > > to a standard way if it was agreed by every vendor. > > > > received and completed descriptors are very basic and I assume any > vendor would support those.
At least it was not supported by virtio. > If we go with vendor stats, how can we > communicate the information to userspace? Currenlty we use netlink > attributes defined to pass this information. It can be done exactly as what have been done in the patch, we can document it as vendor stats. > > > > > > > > > > > > > > > I wonder if it's better > > > > > > to use "vendor" prefix in the protocol, then we use this instead: > > > > > > > > > > > > vdpa dev vendor-stats show vdpa-a > > > > > > > > > > > May be. Lets evaluate if stats of this patch are generic enough or > > > > > not. > > > > > > > > > > > Or if we want to make it standard is exposing virtio index better? > > > > > > > > > > > > qid 0 last_avail_idx X avail_idx Y last_used_idx M used_idx N > > > > > > > > > > > I did consider this option a while back. Shows indices are equally > > > > > useful. > > > > > I think we should show that as vq info, along with other VQ > > > > > attributes (addr, len). > > > > > > > > That may work but it looks to me the receiced_desc/completed_desc is > > > > also per vq. > > > > > > > > Another question is that is it more useful to use buffers instead of > > > > descriptors? E.g how indirect descriptors are counted. > > > > > > > > > > I think it's descriptors so indirect descriptors are counted once but I > > > need to verify that. > > > > > > > > $ vdpa dev show vq > > > > > > > > > > But showing indices are not less statistics and more current state of > > > > > the queue. > > > > > For example roll over of the indices won't cover absolute number of > > > > > descriptors processed for the queue. > > > > > And even if we make them u64 (not good), non_developer end user needs > > > > > to keep using side calculator to count the delta. > > > > > > > > How about exposing those raw indices via the protocol and letting the > > > > vdpa tool calculate for us? > > > > > > > > > > counters are 16 bit per the virtio spec so I don't know how you could > > > handle rolover without losing information. > > > > So at most 1 rollover I guess. So it's not hard by comparing the > > indices. E.g the if last_avil_idx(device avail idx) > avail_idx, we > > know there's one? > > > > I am not sure I am following you. You do query twice. You can never know > how many rounds the virtqueue has gone through so the information is > useless. Ok, I think I get you. So I wonder if it's more useful to use device specific counters. For networking, it could be packets send/received etc. Thanks > > > Thanks > > > > > > > > > Thanks > > > > > > > > > > > > > > So I think useful q indices belong to q info. > > > > > > > > > > > > > > > _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
