> -----Original Message----- > From: Maxime Coquelin <maxime.coque...@redhat.com> > Sent: Wednesday, June 7, 2023 10:59 PM > To: Xia, Chenbo <chenbo....@intel.com>; dev@dpdk.org; > david.march...@redhat.com; m...@redhat.com; f...@redhat.com; > jasow...@redhat.com; Liang, Cunming <cunming.li...@intel.com>; Xie, Yongji > <xieyon...@bytedance.com>; echau...@redhat.com; epere...@redhat.com; > amore...@redhat.com; l...@redhat.com > Subject: Re: [PATCH v5 00/26] Add VDUSE support to Vhost library > > > > On 6/7/23 08:48, Xia, Chenbo wrote: > > Hi Maxime, > > > >> -----Original Message----- > >> From: Maxime Coquelin <maxime.coque...@redhat.com> > >> Sent: Tuesday, June 6, 2023 4:18 PM > >> To: dev@dpdk.org; Xia, Chenbo <chenbo....@intel.com>; > >> david.march...@redhat.com; m...@redhat.com; f...@redhat.com; > >> jasow...@redhat.com; Liang, Cunming <cunming.li...@intel.com>; Xie, > Yongji > >> <xieyon...@bytedance.com>; echau...@redhat.com; epere...@redhat.com; > >> amore...@redhat.com; l...@redhat.com > >> Cc: Maxime Coquelin <maxime.coque...@redhat.com> > >> Subject: [PATCH v5 00/26] Add VDUSE support to Vhost library > >> > >> This series introduces a new type of backend, VDUSE, > >> to the Vhost library. > >> > >> VDUSE stands for vDPA device in Userspace, it enables > >> implementing a Virtio device in userspace and have it > >> attached to the Kernel vDPA bus. > >> > >> Once attached to the vDPA bus, it can be used either by > >> Kernel Virtio drivers, like virtio-net in our case, via > >> the virtio-vdpa driver. Doing that, the device is visible > >> to the Kernel networking stack and is exposed to userspace > >> as a regular netdev. > >> > >> It can also be exposed to userspace thanks to the > >> vhost-vdpa driver, via a vhost-vdpa chardev that can be > >> passed to QEMU or Virtio-user PMD. > >> > >> While VDUSE support is already available in upstream > >> Kernel, a couple of patches are required to support > >> network device type: > >> > >> https://gitlab.com/mcoquelin/linux/-/tree/vduse_networking_rfc > >> > >> In order to attach the created VDUSE device to the vDPA > >> bus, a recent iproute2 version containing the vdpa tool is > >> required. > >> > >> Benchmark results: > >> ================== > >> > >> On this v2, PVP reference benchmark has been run & compared with > >> Vhost-user. > >> > >> When doing macswap forwarding in the worload, no difference is seen. > >> When doing io forwarding in the workload, we see 4% performance > >> degradation with VDUSE, comapred to Vhost-user/Virtio-user. It is > >> explained by the use of the IOTLB layer in the Vhost-library when using > >> VDUSE, whereas Vhost-user/Virtio-user does not make use of it. > >> > >> Usage: > >> ====== > >> > >> 1. Probe required Kernel modules > >> # modprobe vdpa > >> # modprobe vduse > >> # modprobe virtio-vdpa > >> > >> 2. Build (require vduse kernel headers to be available) > >> # meson build > >> # ninja -C build > >> > >> 3. Create a VDUSE device (vduse0) using Vhost PMD with > >> testpmd (with 4 queue pairs in this example) > >> # ./build/app/dpdk-testpmd --no-pci -- > >> vdev=net_vhost0,iface=/dev/vduse/vduse0,queues=4 --log-level=*:9 -- -i > -- > >> txq=4 --rxq=4 > >> > >> 4. Attach the VDUSE device to the vDPA bus > >> # vdpa dev add name vduse0 mgmtdev vduse > >> => The virtio-net netdev shows up (eth0 here) > >> # ip l show eth0 > >> 21: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP > >> mode DEFAULT group default qlen 1000 > >> link/ether c2:73:ea:a7:68:6d brd ff:ff:ff:ff:ff:ff > >> > >> 5. Start/stop traffic in testpmd > >> testpmd> start > >> testpmd> show port stats 0 > >> ######################## NIC statistics for port 0 > >> ######################## > >> RX-packets: 11 RX-missed: 0 RX-bytes: 1482 > >> RX-errors: 0 > >> RX-nombuf: 0 > >> TX-packets: 1 TX-errors: 0 TX-bytes: 62 > >> > >> Throughput (since last show) > >> Rx-pps: 0 Rx-bps: 0 > >> Tx-pps: 0 Tx-bps: 0 > >> > >> > ########################################################################## > >> ## > >> testpmd> stop > >> > >> 6. Detach the VDUSE device from the vDPA bus > >> # vdpa dev del vduse0 > >> > >> 7. Quit testpmd > >> testpmd> quit > >> > >> Known issues & remaining work: > >> ============================== > >> - Fix issue in FD manager (still polling while FD has been removed) > >> - Add Netlink support in Vhost library > >> - Support device reconnection > >> -> a temporary patch to support reconnection via a tmpfs file is > >> available, > >> upstream solution would be in-kernel and is being developed. > >> -> https://gitlab.com/mcoquelin/dpdk-next-virtio/- > >> /commit/5ad06ce14159a9ce36ee168dd13ef389cec91137 > >> - Support packed ring > >> - Provide more performance benchmark results > >> > >> Changes in v5: > >> ============== > >> - Delay starting/stopping the device to after having replied to the > VDUSE > >> event in order to avoid a deadlock encountered when testing with OVS. > > > > Could you explain more to help me understand the deadlock issue? > > Sure. > > The V5 fixes an ABBA deadlock involving OVS mutex and kernel > rtnl_lock(), two OVS threads and the vdpa tool process. > > We have an OVS bridge with a mlx5 port already added. > We add the vduse port to the same bridge. > Then we use the iproute2 vdpa tool to attach the vduse device the the > kernel vdpa bus. when doing this the rtnl lock is taken when the virtio- > net device is probed, and VDUSE_SET_STATUS gets sent and waits for its > reply. > > This VDUSE_SET_STATUS request is handled by the DPDK VDUSE event > handler, and if DRIVER_OK bit is set the Vhsot .new_device() callback is > called, which triggers a bridge reconfiguration. > > On bridge reconfiguration, the mlx5 port takes the OVS mutex and > performs an ioctl() which tries to take the rtnl lock, but is is already > owned by the vdpa tool. > > The vduse_events thread is stucked waiting for the OVS mutex, so the > reply to the VDUSE_SET_STATUS event is never sent, and the vdpa tool > process is stucked for 30 seconds, until a timeout happens. > > When the timeourt happen, everything is unblocked, but the VDUSE device > has been marked as broken, and so not usable anymore. > > I could reproduce and provide you the backtraces of the different > threads if you wish. > > Anyway, I think it makes sense to perform the device startup after > having replied to VDUSE_SET_STATUS request, as it just mean the device > has taken into account the new status of the driver. > > Hope it clarifies, let me know if you need more details.
It's very clear! Thanks Maxime for the explanation! /Chenbo > > Thanks, > Maxime > > > Thanks, > > Chenbo > > > >> - Mention reconnection support lack in the release note. > >> > >> Changes in v4: > >> ============== > >> - Applied patch 1 and patch 2 from v3 > >> - Rebased on top of Eelco series > >> - Fix coredump clear in IOTLB cache removal (David) > >> - Remove uneeded ret variable in vhost_vring_inject_irq (David) > >> - Fixed release note (David, Chenbo) > >> > >> Changes in v2/v3: > >> ================= > >> - Fixed mem_set_dump() parameter (patch 4) > >> - Fixed accidental comment change (patch 7, Chenbo) > >> - Change from __builtin_ctz to __builtin_ctzll (patch 9, Chenbo) > >> - move change from patch 12 to 13 (Chenbo) > >> - Enable locks annotation for control queue (Patch 17) > >> - Send control queue notification when used descriptors enqueued (Patch > 17) > >> - Lock control queue IOTLB lock (Patch 17) > >> - Fix error path in virtio_net_ctrl_pop() (Patch 17, Chenbo) > >> - Set VDUSE dev FD as NONBLOCK (Patch 18) > >> - Enable more Virtio features (Patch 18) > >> - Remove calls to pthread_setcancelstate() (Patch 22) > >> - Add calls to fdset_pipe_notify() when adding and deleting FDs from a > set > >> (Patch 22) > >> - Use RTE_DIM() to get requests string array size (Patch 22) > >> - Set reply result for IOTLB update message (Patch 25, Chenbo) > >> - Fix queues enablement with multiqueue (Patch 26) > >> - Move kickfd creation for better logging (Patch 26) > >> - Improve logging (Patch 26) > >> - Uninstall cvq kickfd in case of handler installation failure (Patch > 27) > >> - Enable CVQ notifications once handler is installed (Patch 27) > >> - Don't advertise multiqueue and control queue if app only request > single > >> queue pair (Patch 27) > >> - Add release notes > >> > >> Maxime Coquelin (26): > >> vhost: fix IOTLB entries overlap check with previous entry > >> vhost: add helper of IOTLB entries coredump > >> vhost: add helper for IOTLB entries shared page check > >> vhost: don't dump unneeded pages with IOTLB > >> vhost: change to single IOTLB cache per device > >> vhost: add offset field to IOTLB entries > >> vhost: add page size info to IOTLB entry > >> vhost: retry translating IOVA after IOTLB miss > >> vhost: introduce backend ops > >> vhost: add IOTLB cache entry removal callback > >> vhost: add helper for IOTLB misses > >> vhost: add helper for interrupt injection > >> vhost: add API to set max queue pairs > >> net/vhost: use API to set max queue pairs > >> vhost: add control virtqueue support > >> vhost: add VDUSE device creation and destruction > >> vhost: add VDUSE callback for IOTLB miss > >> vhost: add VDUSE callback for IOTLB entry removal > >> vhost: add VDUSE callback for IRQ injection > >> vhost: add VDUSE events handler > >> vhost: add support for virtqueue state get event > >> vhost: add support for VDUSE status set event > >> vhost: add support for VDUSE IOTLB update event > >> vhost: add VDUSE device startup > >> vhost: add multiqueue support to VDUSE > >> vhost: add VDUSE device stop > >> > >> doc/guides/prog_guide/vhost_lib.rst | 4 + > >> doc/guides/rel_notes/release_23_07.rst | 12 + > >> drivers/net/vhost/rte_eth_vhost.c | 3 + > >> lib/vhost/iotlb.c | 333 +++++++------ > >> lib/vhost/iotlb.h | 45 +- > >> lib/vhost/meson.build | 5 + > >> lib/vhost/rte_vhost.h | 17 + > >> lib/vhost/socket.c | 72 ++- > >> lib/vhost/vduse.c | 646 > +++++++++++++++++++++++++ > >> lib/vhost/vduse.h | 33 ++ > >> lib/vhost/version.map | 1 + > >> lib/vhost/vhost.c | 70 ++- > >> lib/vhost/vhost.h | 57 ++- > >> lib/vhost/vhost_user.c | 51 +- > >> lib/vhost/vhost_user.h | 2 +- > >> lib/vhost/virtio_net_ctrl.c | 286 +++++++++++ > >> lib/vhost/virtio_net_ctrl.h | 10 + > >> 17 files changed, 1409 insertions(+), 238 deletions(-) > >> create mode 100644 lib/vhost/vduse.c > >> create mode 100644 lib/vhost/vduse.h > >> create mode 100644 lib/vhost/virtio_net_ctrl.c > >> create mode 100644 lib/vhost/virtio_net_ctrl.h > >> > >> -- > >> 2.40.1 > >
