| Message ID | 1569526167-71339-1-git-send-email-u9012063@gmail.com |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | [ovs-dev,PATCHv5] netdev-afxdp: Add need_wakeup supprt. | expand |
On 26 Sep 2019, at 21:29, William Tu wrote: > The patch adds support for using need_wakeup flag in AF_XDP rings. > A new option, use_need_wakeup, is added. When this option is used, > it means that OVS has to explicitly wake up the kernel RX, using > poll() > syscall and wake up TX, using sendto() syscall. This feature improves > the performance by avoiding unnecessary sendto syscalls for TX. > For RX, instead of kernel always busy-spinning on fille queue, OVS > wakes > up the kernel RX processing when fill queue is replenished. > > The need_wakeup feature is merged into Linux kernel bpf-next tee with > commit > 77cd0d7b3f25 ("xsk: add support for need_wakeup flag in AF_XDP rings") > and > OVS enables it by default. Running the feature before this version > causes > xsk bind fails, please use options:use_need_wakeup=false to disable > it. > If users enable it but runs in an older version of libbpf, then the > need_wakeup feature has no effect, and a warning message is logged. > > For virtual interface, it's better set use_need_wakeup=false, since > the virtual device's AF_XDP xmit is synchronous: the sendto syscall > enters kernel and process the TX packet on tx queue directly. > > On Intel Xeon E5-2620 v3 2.4GHz system, performance of physical port > to physical port improves from 6.1Mpps to 7.3Mpps. > > Suggested-by: Ilya Maximets <i.maximets@ovn.org> > Signed-off-by: William Tu <u9012063@gmail.com> Did a quick test, and all works fine. Acke’ed based on previous review and delta… Acked-by: Eelco Chaudron <echaudro@redhat.com>
> > The patch adds support for using need_wakeup flag in AF_XDP rings. > A new option, use_need_wakeup, is added. When this option is used, > it means that OVS has to explicitly wake up the kernel RX, using poll() > syscall and wake up TX, using sendto() syscall. This feature improves > the performance by avoiding unnecessary sendto syscalls for TX. > For RX, instead of kernel always busy-spinning on fille queue, OVS wakes > up the kernel RX processing when fill queue is replenished. > > The need_wakeup feature is merged into Linux kernel bpf-next tee with > commit > 77cd0d7b3f25 ("xsk: add support for need_wakeup flag in AF_XDP rings") > and > OVS enables it by default. Running the feature before this version causes > xsk bind fails, please use options:use_need_wakeup=false to disable it. > If users enable it but runs in an older version of libbpf, then the > need_wakeup feature has no effect, and a warning message is logged. > > For virtual interface, it's better set use_need_wakeup=false, since > the virtual device's AF_XDP xmit is synchronous: the sendto syscall > enters kernel and process the TX packet on tx queue directly. > > On Intel Xeon E5-2620 v3 2.4GHz system, performance of physical port > to physical port improves from 6.1Mpps to 7.3Mpps. Hi William, Thanks for the patch. I'm wondering if/how you've pinned the IRQs for the physical ports in the test above. Are the IRQs pinned to standalone cores or does the PMD thread share the same core? I'd be interested in seeing performance results for both, if you have them. Thanks, Ciara > > Suggested-by: Ilya Maximets <i.maximets@ovn.org> > Signed-off-by: William Tu <u9012063@gmail.com> > ---
On Wed, Oct 16, 2019 at 9:13 AM Loftus, Ciara <ciara.loftus@intel.com> wrote: > > > > > The patch adds support for using need_wakeup flag in AF_XDP rings. > > A new option, use_need_wakeup, is added. When this option is used, > > it means that OVS has to explicitly wake up the kernel RX, using poll() > > syscall and wake up TX, using sendto() syscall. This feature improves > > the performance by avoiding unnecessary sendto syscalls for TX. > > For RX, instead of kernel always busy-spinning on fille queue, OVS wakes > > up the kernel RX processing when fill queue is replenished. > > > > The need_wakeup feature is merged into Linux kernel bpf-next tee with > > commit > > 77cd0d7b3f25 ("xsk: add support for need_wakeup flag in AF_XDP rings") > > and > > OVS enables it by default. Running the feature before this version causes > > xsk bind fails, please use options:use_need_wakeup=false to disable it. > > If users enable it but runs in an older version of libbpf, then the > > need_wakeup feature has no effect, and a warning message is logged. > > > > For virtual interface, it's better set use_need_wakeup=false, since > > the virtual device's AF_XDP xmit is synchronous: the sendto syscall > > enters kernel and process the TX packet on tx queue directly. > > > > On Intel Xeon E5-2620 v3 2.4GHz system, performance of physical port > > to physical port improves from 6.1Mpps to 7.3Mpps. > > > Hi William, > > Thanks for the patch. > I'm wondering if/how you've pinned the IRQs for the physical ports in the test above. > Are the IRQs pinned to standalone cores or does the PMD thread share the same core? > I'd be interested in seeing performance results for both, if you have them. > > Thanks, > Ciara > Hi Ciara, I think this is sharing the same core. I don't have both results. Let me get back to you later. Thank you! William
On 26.09.2019 21:29, William Tu wrote: > The patch adds support for using need_wakeup flag in AF_XDP rings. > A new option, use_need_wakeup, is added. When this option is used, > it means that OVS has to explicitly wake up the kernel RX, using poll() > syscall and wake up TX, using sendto() syscall. This feature improves > the performance by avoiding unnecessary sendto syscalls for TX. > For RX, instead of kernel always busy-spinning on fille queue, OVS wakes > up the kernel RX processing when fill queue is replenished. > > The need_wakeup feature is merged into Linux kernel bpf-next tee with commit > 77cd0d7b3f25 ("xsk: add support for need_wakeup flag in AF_XDP rings") and > OVS enables it by default. Running the feature before this version causes > xsk bind fails, please use options:use_need_wakeup=false to disable it. > If users enable it but runs in an older version of libbpf, then the > need_wakeup feature has no effect, and a warning message is logged. > > For virtual interface, it's better set use_need_wakeup=false, since > the virtual device's AF_XDP xmit is synchronous: the sendto syscall > enters kernel and process the TX packet on tx queue directly. > > On Intel Xeon E5-2620 v3 2.4GHz system, performance of physical port > to physical port improves from 6.1Mpps to 7.3Mpps. > > Suggested-by: Ilya Maximets <i.maximets@ovn.org> > Signed-off-by: William Tu <u9012063@gmail.com> > --- > v5: > - address feedback from Ilya > - update commit msg about kernel version using bpf-next tree > - remove __func__, and use DBG in log_ > - fix alignment > - remove the kernel version requirement for need_wakeup, we can > wait until tag is available > > v4: > - move use_need_wakeup check inside xsk_rx_wakeup_if_needed > > v3: > - add warning when user enables it but libbpf not support it > - revise documentation > > v2: > - address feedbacks from Ilya and Eelco > - add options:use_need_wakeup, default to true > - remove poll timeout=1sec, make poll() return immediately > - naming change: rename to xsk_rx_wakeup_if_needing > - fix indents and return value for errno > --- > Documentation/intro/install/afxdp.rst | 15 ++++- > acinclude.m4 | 5 ++ > lib/netdev-afxdp.c | 108 ++++++++++++++++++++++++++++++---- > lib/netdev-linux-private.h | 2 + > vswitchd/vswitch.xml | 12 ++++ > 5 files changed, 126 insertions(+), 16 deletions(-) > > diff --git a/Documentation/intro/install/afxdp.rst b/Documentation/intro/install/afxdp.rst > index 820e9d993d8f..545516b2bbec 100644 > --- a/Documentation/intro/install/afxdp.rst > +++ b/Documentation/intro/install/afxdp.rst > @@ -176,9 +176,18 @@ in :doc:`general`:: > ovs-vswitchd ... > ovs-vsctl -- add-br br0 -- set Bridge br0 datapath_type=netdev > > -Make sure your device driver support AF_XDP, and to use 1 PMD (on core 4) > -on 1 queue (queue 0) device, configure these options: **pmd-cpu-mask, > -pmd-rxq-affinity, and n_rxq**. The **xdpmode** can be "drv" or "skb":: > +Make sure your device driver support AF_XDP, netdev-afxdp supports > +the following additional options (see man ovs-vswitchd.conf.db for > +more details): > + > + * **xdpmode**: use "drv" for driver mode, or "skb" for skb mode. > + > + * **use_need_wakeup**: disable by setting to "false", otherwise default > + is "true" > + > +For example, to use 1 PMD (on core 4) on 1 queue (queue 0) device, > +configure these options: **pmd-cpu-mask, pmd-rxq-affinity, and n_rxq**. > +The **xdpmode** can be "drv" or "skb":: > > ethtool -L enp2s0 combined 1 > ovs-vsctl set Open_vSwitch . other_config:pmd-cpu-mask=0x10 > diff --git a/acinclude.m4 b/acinclude.m4 > index f0e38898b17a..f1ecb86adf7c 100644 > --- a/acinclude.m4 > +++ b/acinclude.m4 > @@ -276,6 +276,11 @@ AC_DEFUN([OVS_CHECK_LINUX_AF_XDP], [ > [Define to 1 if AF_XDP support is available and enabled.]) > LIBBPF_LDADD=" -lbpf -lelf" > AC_SUBST([LIBBPF_LDADD]) > + > + AC_CHECK_DECL([xsk_ring_prod__needs_wakeup], [ > + AC_DEFINE([HAVE_XDP_NEED_WAKEUP], [1], > + [XDP need wakeup support detected in xsk.h.]) > + ], [], [[#include <bpf/xsk.h>]]) > fi > AM_CONDITIONAL([HAVE_AF_XDP], test "$AF_XDP_ENABLE" = true) > ]) > diff --git a/lib/netdev-afxdp.c b/lib/netdev-afxdp.c > index 6e01803272aa..fee9413bfd0a 100644 > --- a/lib/netdev-afxdp.c > +++ b/lib/netdev-afxdp.c > @@ -26,6 +26,7 @@ > #include <linux/rtnetlink.h> > #include <linux/if_xdp.h> > #include <net/if.h> > +#include <poll.h> > #include <stdlib.h> > #include <sys/resource.h> > #include <sys/socket.h> > @@ -82,7 +83,7 @@ BUILD_ASSERT_DECL(PROD_NUM_DESCS == CONS_NUM_DESCS); > #define UMEM2DESC(elem, base) ((uint64_t)((char *)elem - (char *)base)) > > static struct xsk_socket_info *xsk_configure(int ifindex, int xdp_queue_id, > - int mode); > + int mode, bool use_need_wakeup); > static void xsk_remove_xdp_program(uint32_t ifindex, int xdpmode); > static void xsk_destroy(struct xsk_socket_info *xsk); > static int xsk_configure_all(struct netdev *netdev); > @@ -117,6 +118,54 @@ struct xsk_socket_info { > atomic_uint64_t tx_dropped; > }; > > +#ifdef HAVE_XDP_NEED_WAKEUP > +static inline void > +xsk_rx_wakeup_if_needed(struct xsk_umem_info *umem, > + struct netdev *netdev, int fd) > +{ > + struct netdev_linux *dev = netdev_linux_cast(netdev); > + struct pollfd pfd; > + int ret; > + > + if (!dev->use_need_wakeup) { > + return; > + } > + > + if (xsk_ring_prod__needs_wakeup(&umem->fq)) { > + pfd.fd = fd; > + pfd.events = POLLIN; > + > + ret = poll(&pfd, 1, 0); > + if (OVS_UNLIKELY(ret < 0)) { > + VLOG_WARN_RL(&rl, "%s: error polling rx fd: %s.", > + netdev_get_name(netdev), > + ovs_strerror(errno)); > + } > + } > +} > + > +static inline bool > +xsk_tx_need_wakeup(struct xsk_socket_info *xsk_info) > +{ > + return xsk_ring_prod__needs_wakeup(&xsk_info->tx); > +} > + > +#else /* !HAVE_XDP_NEED_WAKEUP */ > +static inline void > +xsk_rx_wakeup_if_needed(struct xsk_umem_info *umem OVS_UNUSED, > + struct netdev *netdev OVS_UNUSED, > + int fd OVS_UNUSED) > +{ > + /* Nothing. */ > +} > + > +static inline bool > +xsk_tx_need_wakeup(struct xsk_socket_info *xsk_info OVS_UNUSED) > +{ > + return true; > +} > +#endif /* HAVE_XDP_NEED_WAKEUP */ > + > static void > netdev_afxdp_cleanup_unused_pool(struct unused_pool *pool) > { > @@ -234,7 +283,7 @@ xsk_configure_umem(void *buffer, uint64_t size, int xdpmode) > > static struct xsk_socket_info * > xsk_configure_socket(struct xsk_umem_info *umem, uint32_t ifindex, > - uint32_t queue_id, int xdpmode) > + uint32_t queue_id, int xdpmode, bool use_need_wakeup) > { > struct xsk_socket_config cfg; > struct xsk_socket_info *xsk; > @@ -257,6 +306,12 @@ xsk_configure_socket(struct xsk_umem_info *umem, uint32_t ifindex, > cfg.xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST | XDP_FLAGS_SKB_MODE; > } > > + if (use_need_wakeup) { > +#ifdef HAVE_XDP_NEED_WAKEUP > + cfg.bind_flags |= XDP_USE_NEED_WAKEUP; > +#endif > + } > + > if (if_indextoname(ifindex, devname) == NULL) { > VLOG_ERR("ifindex %d to devname failed (%s)", > ifindex, ovs_strerror(errno)); > @@ -267,9 +322,11 @@ xsk_configure_socket(struct xsk_umem_info *umem, uint32_t ifindex, > ret = xsk_socket__create(&xsk->xsk, devname, queue_id, umem->umem, > &xsk->rx, &xsk->tx, &cfg); > if (ret) { > - VLOG_ERR("xsk_socket__create failed (%s) mode: %s qid: %d", > + VLOG_ERR("xsk_socket__create failed (%s) mode: %s " > + "use_need_wakeup: %s qid: %d", > ovs_strerror(errno), > xdpmode == XDP_COPY ? "SKB": "DRV", > + use_need_wakeup ? "true" : "false", > queue_id); > free(xsk); > return NULL; > @@ -311,7 +368,8 @@ xsk_configure_socket(struct xsk_umem_info *umem, uint32_t ifindex, > } > > static struct xsk_socket_info * > -xsk_configure(int ifindex, int xdp_queue_id, int xdpmode) > +xsk_configure(int ifindex, int xdp_queue_id, int xdpmode, > + bool use_need_wakeup) > { > struct xsk_socket_info *xsk; > struct xsk_umem_info *umem; > @@ -334,7 +392,8 @@ xsk_configure(int ifindex, int xdp_queue_id, int xdpmode) > > VLOG_DBG("Allocated umem pool at 0x%"PRIxPTR, (uintptr_t) umem); > > - xsk = xsk_configure_socket(umem, ifindex, xdp_queue_id, xdpmode); > + xsk = xsk_configure_socket(umem, ifindex, xdp_queue_id, xdpmode, > + use_need_wakeup); > if (!xsk) { > /* Clean up umem and xpacket pool. */ > if (xsk_umem__delete(umem->umem)) { > @@ -365,9 +424,12 @@ xsk_configure_all(struct netdev *netdev) > > /* Configure each queue. */ > for (i = 0; i < n_rxq; i++) { > - VLOG_INFO("%s: configure queue %d mode %s", __func__, i, > - dev->xdpmode == XDP_COPY ? "SKB" : "DRV"); > - xsk_info = xsk_configure(ifindex, i, dev->xdpmode); > + VLOG_DBG("%s: configure queue %d mode %s use_need_wakeup %s.", > + netdev_get_name(netdev), i, > + dev->xdpmode == XDP_COPY ? "SKB" : "DRV", > + dev->use_need_wakeup ? "true" : "false"); > + xsk_info = xsk_configure(ifindex, i, dev->xdpmode, > + dev->use_need_wakeup); > if (!xsk_info) { > VLOG_ERR("Failed to create AF_XDP socket on queue %d.", i); > dev->xsks[i] = NULL; > @@ -459,6 +521,7 @@ netdev_afxdp_set_config(struct netdev *netdev, const struct smap *args, > struct netdev_linux *dev = netdev_linux_cast(netdev); > const char *str_xdpmode; > int xdpmode, new_n_rxq; > + bool need_wakeup; > > ovs_mutex_lock(&dev->mutex); > new_n_rxq = MAX(smap_get_int(args, "n_rxq", NR_QUEUE), 1); > @@ -481,10 +544,19 @@ netdev_afxdp_set_config(struct netdev *netdev, const struct smap *args, > return EINVAL; > } > > + need_wakeup = smap_get_bool(args, "use_need_wakeup", true); > + if (need_wakeup) { > +#ifndef HAVE_XDP_NEED_WAKEUP > + VLOG_WARN("XDP need_wakeup is not supported in libbpf."); This warning breaks all the tests on system without need_wakeup support. It seems better to enable this feature by default only if supported by libbpf. One more thing that we need to actually drop need_wakeup to false here, otherwise get_config() and some log messages will report wrong information. Suggesting following incremental: diff --git a/lib/netdev-afxdp.c b/lib/netdev-afxdp.c index a516cc727..60259bdd3 100644 --- a/lib/netdev-afxdp.c +++ b/lib/netdev-afxdp.c @@ -68,6 +68,12 @@ static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 20); #define PROD_NUM_DESCS XSK_RING_PROD__DEFAULT_NUM_DESCS #define CONS_NUM_DESCS XSK_RING_CONS__DEFAULT_NUM_DESCS +#ifdef HAVE_XDP_NEED_WAKEUP +#define NEED_WAKEUP_DEFAULT true +#else +#define NEED_WAKEUP_DEFAULT false +#endif + /* The worst case is all 4 queues TX/CQ/RX/FILL are full + some packets * still on processing in threads. Number of packets currently in OVS * processing is hard to estimate because it depends on number of ports. @@ -307,11 +313,11 @@ xsk_configure_socket(struct xsk_umem_info *umem, uint32_t ifindex, cfg.xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST | XDP_FLAGS_SKB_MODE; } - if (use_need_wakeup) { #ifdef HAVE_XDP_NEED_WAKEUP + if (use_need_wakeup) { cfg.bind_flags |= XDP_USE_NEED_WAKEUP; -#endif } +#endif if (if_indextoname(ifindex, devname) == NULL) { VLOG_ERR("ifindex %d to devname failed (%s)", @@ -545,12 +551,13 @@ netdev_afxdp_set_config(struct netdev *netdev, const struct smap *args, return EINVAL; } - need_wakeup = smap_get_bool(args, "use_need_wakeup", true); - if (need_wakeup) { + need_wakeup = smap_get_bool(args, "use_need_wakeup", NEED_WAKEUP_DEFAULT); #ifndef HAVE_XDP_NEED_WAKEUP + if (need_wakeup) { VLOG_WARN("XDP need_wakeup is not supported in libbpf."); -#endif + need_wakeup = false; } +#endif if (dev->requested_n_rxq != new_n_rxq || dev->requested_xdpmode != xdpmode @@ -1049,7 +1056,7 @@ netdev_afxdp_construct(struct netdev *netdev) dev->requested_n_rxq = NR_QUEUE; dev->requested_xdpmode = XDP_COPY; - dev->requested_need_wakeup = true; + dev->requested_need_wakeup = NEED_WAKEUP_DEFAULT; dev->xsks = NULL; dev->tx_locks = NULL; diff --git a/vswitchd/vswitch.xml b/vswitchd/vswitch.xml index 24d061891..decccfe84 100644 --- a/vswitchd/vswitch.xml +++ b/vswitchd/vswitch.xml @@ -3130,7 +3130,7 @@ ovs-vsctl add-port br0 p0 -- set Interface p0 type=patch options:peer=p1 \ syscall and wakes up TX, using sendto() syscall. For physical devices, this feature improves the performance by avoiding unnecessary sendto syscalls. - Defaults is true. + Defaults to true if supported by libbpf. </p> </column> --- Some updates about default value also will be needed in commit message and, probably, in afxdp docs. Best regards, Ilya Maximets.
On Fri, Oct 18, 2019 at 05:14:46PM +0200, Ilya Maximets wrote: > On 26.09.2019 21:29, William Tu wrote: > >The patch adds support for using need_wakeup flag in AF_XDP rings. > >A new option, use_need_wakeup, is added. When this option is used, > >it means that OVS has to explicitly wake up the kernel RX, using poll() > >syscall and wake up TX, using sendto() syscall. This feature improves > >the performance by avoiding unnecessary sendto syscalls for TX. > >For RX, instead of kernel always busy-spinning on fille queue, OVS wakes > >up the kernel RX processing when fill queue is replenished. > > > >The need_wakeup feature is merged into Linux kernel bpf-next tee with commit > >77cd0d7b3f25 ("xsk: add support for need_wakeup flag in AF_XDP rings") and > >OVS enables it by default. Running the feature before this version causes > >xsk bind fails, please use options:use_need_wakeup=false to disable it. > >If users enable it but runs in an older version of libbpf, then the > >need_wakeup feature has no effect, and a warning message is logged. > > > >For virtual interface, it's better set use_need_wakeup=false, since > >the virtual device's AF_XDP xmit is synchronous: the sendto syscall > >enters kernel and process the TX packet on tx queue directly. > > > >On Intel Xeon E5-2620 v3 2.4GHz system, performance of physical port > >to physical port improves from 6.1Mpps to 7.3Mpps. > > > >Suggested-by: Ilya Maximets <i.maximets@ovn.org> > >Signed-off-by: William Tu <u9012063@gmail.com> > >--- > >v5: > >- address feedback from Ilya > > - update commit msg about kernel version using bpf-next tree > > - remove __func__, and use DBG in log_ > > - fix alignment > > - remove the kernel version requirement for need_wakeup, we can > > wait until tag is available > > > >v4: > >- move use_need_wakeup check inside xsk_rx_wakeup_if_needed > > > >v3: > >- add warning when user enables it but libbpf not support it > >- revise documentation > > > >v2: > >- address feedbacks from Ilya and Eelco > >- add options:use_need_wakeup, default to true > >- remove poll timeout=1sec, make poll() return immediately > >- naming change: rename to xsk_rx_wakeup_if_needing > >- fix indents and return value for errno > >--- > > Documentation/intro/install/afxdp.rst | 15 ++++- > > acinclude.m4 | 5 ++ > > lib/netdev-afxdp.c | 108 ++++++++++++++++++++++++++++++---- > > lib/netdev-linux-private.h | 2 + > > vswitchd/vswitch.xml | 12 ++++ > > 5 files changed, 126 insertions(+), 16 deletions(-) > > > >diff --git a/Documentation/intro/install/afxdp.rst b/Documentation/intro/install/afxdp.rst > >index 820e9d993d8f..545516b2bbec 100644 > >--- a/Documentation/intro/install/afxdp.rst > >+++ b/Documentation/intro/install/afxdp.rst > >@@ -176,9 +176,18 @@ in :doc:`general`:: > > ovs-vswitchd ... > > ovs-vsctl -- add-br br0 -- set Bridge br0 datapath_type=netdev > >-Make sure your device driver support AF_XDP, and to use 1 PMD (on core 4) > >-on 1 queue (queue 0) device, configure these options: **pmd-cpu-mask, > >-pmd-rxq-affinity, and n_rxq**. The **xdpmode** can be "drv" or "skb":: > >+Make sure your device driver support AF_XDP, netdev-afxdp supports > >+the following additional options (see man ovs-vswitchd.conf.db for > >+more details): > >+ > >+ * **xdpmode**: use "drv" for driver mode, or "skb" for skb mode. > >+ > >+ * **use_need_wakeup**: disable by setting to "false", otherwise default > >+ is "true" > >+ > >+For example, to use 1 PMD (on core 4) on 1 queue (queue 0) device, > >+configure these options: **pmd-cpu-mask, pmd-rxq-affinity, and n_rxq**. > >+The **xdpmode** can be "drv" or "skb":: > > ethtool -L enp2s0 combined 1 > > ovs-vsctl set Open_vSwitch . other_config:pmd-cpu-mask=0x10 > >diff --git a/acinclude.m4 b/acinclude.m4 > >index f0e38898b17a..f1ecb86adf7c 100644 > >--- a/acinclude.m4 > >+++ b/acinclude.m4 > >@@ -276,6 +276,11 @@ AC_DEFUN([OVS_CHECK_LINUX_AF_XDP], [ > > [Define to 1 if AF_XDP support is available and enabled.]) > > LIBBPF_LDADD=" -lbpf -lelf" > > AC_SUBST([LIBBPF_LDADD]) > >+ > >+ AC_CHECK_DECL([xsk_ring_prod__needs_wakeup], [ > >+ AC_DEFINE([HAVE_XDP_NEED_WAKEUP], [1], > >+ [XDP need wakeup support detected in xsk.h.]) > >+ ], [], [[#include <bpf/xsk.h>]]) > > fi > > AM_CONDITIONAL([HAVE_AF_XDP], test "$AF_XDP_ENABLE" = true) > > ]) > >diff --git a/lib/netdev-afxdp.c b/lib/netdev-afxdp.c > >index 6e01803272aa..fee9413bfd0a 100644 > >--- a/lib/netdev-afxdp.c > >+++ b/lib/netdev-afxdp.c > >@@ -26,6 +26,7 @@ > > #include <linux/rtnetlink.h> > > #include <linux/if_xdp.h> > > #include <net/if.h> > >+#include <poll.h> > > #include <stdlib.h> > > #include <sys/resource.h> > > #include <sys/socket.h> > >@@ -82,7 +83,7 @@ BUILD_ASSERT_DECL(PROD_NUM_DESCS == CONS_NUM_DESCS); > > #define UMEM2DESC(elem, base) ((uint64_t)((char *)elem - (char *)base)) > > static struct xsk_socket_info *xsk_configure(int ifindex, int xdp_queue_id, > >- int mode); > >+ int mode, bool use_need_wakeup); > > static void xsk_remove_xdp_program(uint32_t ifindex, int xdpmode); > > static void xsk_destroy(struct xsk_socket_info *xsk); > > static int xsk_configure_all(struct netdev *netdev); > >@@ -117,6 +118,54 @@ struct xsk_socket_info { > > atomic_uint64_t tx_dropped; > > }; > >+#ifdef HAVE_XDP_NEED_WAKEUP > >+static inline void > >+xsk_rx_wakeup_if_needed(struct xsk_umem_info *umem, > >+ struct netdev *netdev, int fd) > >+{ > >+ struct netdev_linux *dev = netdev_linux_cast(netdev); > >+ struct pollfd pfd; > >+ int ret; > >+ > >+ if (!dev->use_need_wakeup) { > >+ return; > >+ } > >+ > >+ if (xsk_ring_prod__needs_wakeup(&umem->fq)) { > >+ pfd.fd = fd; > >+ pfd.events = POLLIN; > >+ > >+ ret = poll(&pfd, 1, 0); > >+ if (OVS_UNLIKELY(ret < 0)) { > >+ VLOG_WARN_RL(&rl, "%s: error polling rx fd: %s.", > >+ netdev_get_name(netdev), > >+ ovs_strerror(errno)); > >+ } > >+ } > >+} > >+ > >+static inline bool > >+xsk_tx_need_wakeup(struct xsk_socket_info *xsk_info) > >+{ > >+ return xsk_ring_prod__needs_wakeup(&xsk_info->tx); > >+} > >+ > >+#else /* !HAVE_XDP_NEED_WAKEUP */ > >+static inline void > >+xsk_rx_wakeup_if_needed(struct xsk_umem_info *umem OVS_UNUSED, > >+ struct netdev *netdev OVS_UNUSED, > >+ int fd OVS_UNUSED) > >+{ > >+ /* Nothing. */ > >+} > >+ > >+static inline bool > >+xsk_tx_need_wakeup(struct xsk_socket_info *xsk_info OVS_UNUSED) > >+{ > >+ return true; > >+} > >+#endif /* HAVE_XDP_NEED_WAKEUP */ > >+ > > static void > > netdev_afxdp_cleanup_unused_pool(struct unused_pool *pool) > > { > >@@ -234,7 +283,7 @@ xsk_configure_umem(void *buffer, uint64_t size, int xdpmode) > > static struct xsk_socket_info * > > xsk_configure_socket(struct xsk_umem_info *umem, uint32_t ifindex, > >- uint32_t queue_id, int xdpmode) > >+ uint32_t queue_id, int xdpmode, bool use_need_wakeup) > > { > > struct xsk_socket_config cfg; > > struct xsk_socket_info *xsk; > >@@ -257,6 +306,12 @@ xsk_configure_socket(struct xsk_umem_info *umem, uint32_t ifindex, > > cfg.xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST | XDP_FLAGS_SKB_MODE; > > } > >+ if (use_need_wakeup) { > >+#ifdef HAVE_XDP_NEED_WAKEUP > >+ cfg.bind_flags |= XDP_USE_NEED_WAKEUP; > >+#endif > >+ } > >+ > > if (if_indextoname(ifindex, devname) == NULL) { > > VLOG_ERR("ifindex %d to devname failed (%s)", > > ifindex, ovs_strerror(errno)); > >@@ -267,9 +322,11 @@ xsk_configure_socket(struct xsk_umem_info *umem, uint32_t ifindex, > > ret = xsk_socket__create(&xsk->xsk, devname, queue_id, umem->umem, > > &xsk->rx, &xsk->tx, &cfg); > > if (ret) { > >- VLOG_ERR("xsk_socket__create failed (%s) mode: %s qid: %d", > >+ VLOG_ERR("xsk_socket__create failed (%s) mode: %s " > >+ "use_need_wakeup: %s qid: %d", > > ovs_strerror(errno), > > xdpmode == XDP_COPY ? "SKB": "DRV", > >+ use_need_wakeup ? "true" : "false", > > queue_id); > > free(xsk); > > return NULL; > >@@ -311,7 +368,8 @@ xsk_configure_socket(struct xsk_umem_info *umem, uint32_t ifindex, > > } > > static struct xsk_socket_info * > >-xsk_configure(int ifindex, int xdp_queue_id, int xdpmode) > >+xsk_configure(int ifindex, int xdp_queue_id, int xdpmode, > >+ bool use_need_wakeup) > > { > > struct xsk_socket_info *xsk; > > struct xsk_umem_info *umem; > >@@ -334,7 +392,8 @@ xsk_configure(int ifindex, int xdp_queue_id, int xdpmode) > > VLOG_DBG("Allocated umem pool at 0x%"PRIxPTR, (uintptr_t) umem); > >- xsk = xsk_configure_socket(umem, ifindex, xdp_queue_id, xdpmode); > >+ xsk = xsk_configure_socket(umem, ifindex, xdp_queue_id, xdpmode, > >+ use_need_wakeup); > > if (!xsk) { > > /* Clean up umem and xpacket pool. */ > > if (xsk_umem__delete(umem->umem)) { > >@@ -365,9 +424,12 @@ xsk_configure_all(struct netdev *netdev) > > /* Configure each queue. */ > > for (i = 0; i < n_rxq; i++) { > >- VLOG_INFO("%s: configure queue %d mode %s", __func__, i, > >- dev->xdpmode == XDP_COPY ? "SKB" : "DRV"); > >- xsk_info = xsk_configure(ifindex, i, dev->xdpmode); > >+ VLOG_DBG("%s: configure queue %d mode %s use_need_wakeup %s.", > >+ netdev_get_name(netdev), i, > >+ dev->xdpmode == XDP_COPY ? "SKB" : "DRV", > >+ dev->use_need_wakeup ? "true" : "false"); > >+ xsk_info = xsk_configure(ifindex, i, dev->xdpmode, > >+ dev->use_need_wakeup); > > if (!xsk_info) { > > VLOG_ERR("Failed to create AF_XDP socket on queue %d.", i); > > dev->xsks[i] = NULL; > >@@ -459,6 +521,7 @@ netdev_afxdp_set_config(struct netdev *netdev, const struct smap *args, > > struct netdev_linux *dev = netdev_linux_cast(netdev); > > const char *str_xdpmode; > > int xdpmode, new_n_rxq; > >+ bool need_wakeup; > > ovs_mutex_lock(&dev->mutex); > > new_n_rxq = MAX(smap_get_int(args, "n_rxq", NR_QUEUE), 1); > >@@ -481,10 +544,19 @@ netdev_afxdp_set_config(struct netdev *netdev, const struct smap *args, > > return EINVAL; > > } > >+ need_wakeup = smap_get_bool(args, "use_need_wakeup", true); > >+ if (need_wakeup) { > >+#ifndef HAVE_XDP_NEED_WAKEUP > >+ VLOG_WARN("XDP need_wakeup is not supported in libbpf."); > > This warning breaks all the tests on system without need_wakeup support. > It seems better to enable this feature by default only if supported by libbpf. Thank you. I think that's a better idea. > > One more thing that we need to actually drop need_wakeup to false here, > otherwise get_config() and some log messages will report wrong information. > > Suggesting following incremental: > > diff --git a/lib/netdev-afxdp.c b/lib/netdev-afxdp.c > index a516cc727..60259bdd3 100644 > --- a/lib/netdev-afxdp.c > +++ b/lib/netdev-afxdp.c > @@ -68,6 +68,12 @@ static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 20); > #define PROD_NUM_DESCS XSK_RING_PROD__DEFAULT_NUM_DESCS > #define CONS_NUM_DESCS XSK_RING_CONS__DEFAULT_NUM_DESCS > +#ifdef HAVE_XDP_NEED_WAKEUP > +#define NEED_WAKEUP_DEFAULT true > +#else > +#define NEED_WAKEUP_DEFAULT false > +#endif > + > /* The worst case is all 4 queues TX/CQ/RX/FILL are full + some packets > * still on processing in threads. Number of packets currently in OVS > * processing is hard to estimate because it depends on number of ports. > @@ -307,11 +313,11 @@ xsk_configure_socket(struct xsk_umem_info *umem, uint32_t ifindex, > cfg.xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST | XDP_FLAGS_SKB_MODE; > } > - if (use_need_wakeup) { > #ifdef HAVE_XDP_NEED_WAKEUP > + if (use_need_wakeup) { > cfg.bind_flags |= XDP_USE_NEED_WAKEUP; > -#endif > } > +#endif > if (if_indextoname(ifindex, devname) == NULL) { > VLOG_ERR("ifindex %d to devname failed (%s)", > @@ -545,12 +551,13 @@ netdev_afxdp_set_config(struct netdev *netdev, const struct smap *args, > return EINVAL; > } > - need_wakeup = smap_get_bool(args, "use_need_wakeup", true); > - if (need_wakeup) { > + need_wakeup = smap_get_bool(args, "use_need_wakeup", NEED_WAKEUP_DEFAULT); > #ifndef HAVE_XDP_NEED_WAKEUP > + if (need_wakeup) { > VLOG_WARN("XDP need_wakeup is not supported in libbpf."); > -#endif > + need_wakeup = false; > } > +#endif > if (dev->requested_n_rxq != new_n_rxq > || dev->requested_xdpmode != xdpmode > @@ -1049,7 +1056,7 @@ netdev_afxdp_construct(struct netdev *netdev) > dev->requested_n_rxq = NR_QUEUE; > dev->requested_xdpmode = XDP_COPY; > - dev->requested_need_wakeup = true; > + dev->requested_need_wakeup = NEED_WAKEUP_DEFAULT; > dev->xsks = NULL; > dev->tx_locks = NULL; > diff --git a/vswitchd/vswitch.xml b/vswitchd/vswitch.xml > index 24d061891..decccfe84 100644 > --- a/vswitchd/vswitch.xml > +++ b/vswitchd/vswitch.xml > @@ -3130,7 +3130,7 @@ ovs-vsctl add-port br0 p0 -- set Interface p0 type=patch options:peer=p1 \ > syscall and wakes up TX, using sendto() syscall. For physical > devices, this feature improves the performance by avoiding > unnecessary sendto syscalls. > - Defaults is true. > + Defaults to true if supported by libbpf. > </p> > </column> > --- > > Some updates about default value also will be needed in commit message and, > probably, in afxdp docs. OK. the diff works fine. I will re-do the performance number and send out next version. Regards, William > > Best regards, Ilya Maximets.
On Wed, Oct 16, 2019 at 04:13:14PM +0000, Loftus, Ciara wrote: > > > > The patch adds support for using need_wakeup flag in AF_XDP rings. > > A new option, use_need_wakeup, is added. When this option is used, > > it means that OVS has to explicitly wake up the kernel RX, using poll() > > syscall and wake up TX, using sendto() syscall. This feature improves > > the performance by avoiding unnecessary sendto syscalls for TX. > > For RX, instead of kernel always busy-spinning on fille queue, OVS wakes > > up the kernel RX processing when fill queue is replenished. > > > > The need_wakeup feature is merged into Linux kernel bpf-next tee with > > commit > > 77cd0d7b3f25 ("xsk: add support for need_wakeup flag in AF_XDP rings") > > and > > OVS enables it by default. Running the feature before this version causes > > xsk bind fails, please use options:use_need_wakeup=false to disable it. > > If users enable it but runs in an older version of libbpf, then the > > need_wakeup feature has no effect, and a warning message is logged. > > > > For virtual interface, it's better set use_need_wakeup=false, since > > the virtual device's AF_XDP xmit is synchronous: the sendto syscall > > enters kernel and process the TX packet on tx queue directly. > > > > On Intel Xeon E5-2620 v3 2.4GHz system, performance of physical port > > to physical port improves from 6.1Mpps to 7.3Mpps. > > > Hi William, > > Thanks for the patch. > I'm wondering if/how you've pinned the IRQs for the physical ports in the test above. > Are the IRQs pinned to standalone cores or does the PMD thread share the same core? > I'd be interested in seeing performance results for both, if you have them. > > Thanks, > Ciara Hi Ciara, I've sent out a new version for more performance detail. For IRQs, I didn't pinned IRQ to any perticular core. I setup to use core 6 for PMD thread, I can see my softirqd/4 using 100%cpu, and interrupt is spread through different cores (but mostly at CPU9 and CPU10, from /proc/interrupts. Thanks William
diff --git a/Documentation/intro/install/afxdp.rst b/Documentation/intro/install/afxdp.rst index 820e9d993d8f..545516b2bbec 100644 --- a/Documentation/intro/install/afxdp.rst +++ b/Documentation/intro/install/afxdp.rst @@ -176,9 +176,18 @@ in :doc:`general`:: ovs-vswitchd ... ovs-vsctl -- add-br br0 -- set Bridge br0 datapath_type=netdev -Make sure your device driver support AF_XDP, and to use 1 PMD (on core 4) -on 1 queue (queue 0) device, configure these options: **pmd-cpu-mask, -pmd-rxq-affinity, and n_rxq**. The **xdpmode** can be "drv" or "skb":: +Make sure your device driver support AF_XDP, netdev-afxdp supports +the following additional options (see man ovs-vswitchd.conf.db for +more details): + + * **xdpmode**: use "drv" for driver mode, or "skb" for skb mode. + + * **use_need_wakeup**: disable by setting to "false", otherwise default + is "true" + +For example, to use 1 PMD (on core 4) on 1 queue (queue 0) device, +configure these options: **pmd-cpu-mask, pmd-rxq-affinity, and n_rxq**. +The **xdpmode** can be "drv" or "skb":: ethtool -L enp2s0 combined 1 ovs-vsctl set Open_vSwitch . other_config:pmd-cpu-mask=0x10 diff --git a/acinclude.m4 b/acinclude.m4 index f0e38898b17a..f1ecb86adf7c 100644 --- a/acinclude.m4 +++ b/acinclude.m4 @@ -276,6 +276,11 @@ AC_DEFUN([OVS_CHECK_LINUX_AF_XDP], [ [Define to 1 if AF_XDP support is available and enabled.]) LIBBPF_LDADD=" -lbpf -lelf" AC_SUBST([LIBBPF_LDADD]) + + AC_CHECK_DECL([xsk_ring_prod__needs_wakeup], [ + AC_DEFINE([HAVE_XDP_NEED_WAKEUP], [1], + [XDP need wakeup support detected in xsk.h.]) + ], [], [[#include <bpf/xsk.h>]]) fi AM_CONDITIONAL([HAVE_AF_XDP], test "$AF_XDP_ENABLE" = true) ]) diff --git a/lib/netdev-afxdp.c b/lib/netdev-afxdp.c index 6e01803272aa..fee9413bfd0a 100644 --- a/lib/netdev-afxdp.c +++ b/lib/netdev-afxdp.c @@ -26,6 +26,7 @@ #include <linux/rtnetlink.h> #include <linux/if_xdp.h> #include <net/if.h> +#include <poll.h> #include <stdlib.h> #include <sys/resource.h> #include <sys/socket.h> @@ -82,7 +83,7 @@ BUILD_ASSERT_DECL(PROD_NUM_DESCS == CONS_NUM_DESCS); #define UMEM2DESC(elem, base) ((uint64_t)((char *)elem - (char *)base)) static struct xsk_socket_info *xsk_configure(int ifindex, int xdp_queue_id, - int mode); + int mode, bool use_need_wakeup); static void xsk_remove_xdp_program(uint32_t ifindex, int xdpmode); static void xsk_destroy(struct xsk_socket_info *xsk); static int xsk_configure_all(struct netdev *netdev); @@ -117,6 +118,54 @@ struct xsk_socket_info { atomic_uint64_t tx_dropped; }; +#ifdef HAVE_XDP_NEED_WAKEUP +static inline void +xsk_rx_wakeup_if_needed(struct xsk_umem_info *umem, + struct netdev *netdev, int fd) +{ + struct netdev_linux *dev = netdev_linux_cast(netdev); + struct pollfd pfd; + int ret; + + if (!dev->use_need_wakeup) { + return; + } + + if (xsk_ring_prod__needs_wakeup(&umem->fq)) { + pfd.fd = fd; + pfd.events = POLLIN; + + ret = poll(&pfd, 1, 0); + if (OVS_UNLIKELY(ret < 0)) { + VLOG_WARN_RL(&rl, "%s: error polling rx fd: %s.", + netdev_get_name(netdev), + ovs_strerror(errno)); + } + } +} + +static inline bool +xsk_tx_need_wakeup(struct xsk_socket_info *xsk_info) +{ + return xsk_ring_prod__needs_wakeup(&xsk_info->tx); +} + +#else /* !HAVE_XDP_NEED_WAKEUP */ +static inline void +xsk_rx_wakeup_if_needed(struct xsk_umem_info *umem OVS_UNUSED, + struct netdev *netdev OVS_UNUSED, + int fd OVS_UNUSED) +{ + /* Nothing. */ +} + +static inline bool +xsk_tx_need_wakeup(struct xsk_socket_info *xsk_info OVS_UNUSED) +{ + return true; +} +#endif /* HAVE_XDP_NEED_WAKEUP */ + static void netdev_afxdp_cleanup_unused_pool(struct unused_pool *pool) { @@ -234,7 +283,7 @@ xsk_configure_umem(void *buffer, uint64_t size, int xdpmode) static struct xsk_socket_info * xsk_configure_socket(struct xsk_umem_info *umem, uint32_t ifindex, - uint32_t queue_id, int xdpmode) + uint32_t queue_id, int xdpmode, bool use_need_wakeup) { struct xsk_socket_config cfg; struct xsk_socket_info *xsk; @@ -257,6 +306,12 @@ xsk_configure_socket(struct xsk_umem_info *umem, uint32_t ifindex, cfg.xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST | XDP_FLAGS_SKB_MODE; } + if (use_need_wakeup) { +#ifdef HAVE_XDP_NEED_WAKEUP + cfg.bind_flags |= XDP_USE_NEED_WAKEUP; +#endif + } + if (if_indextoname(ifindex, devname) == NULL) { VLOG_ERR("ifindex %d to devname failed (%s)", ifindex, ovs_strerror(errno)); @@ -267,9 +322,11 @@ xsk_configure_socket(struct xsk_umem_info *umem, uint32_t ifindex, ret = xsk_socket__create(&xsk->xsk, devname, queue_id, umem->umem, &xsk->rx, &xsk->tx, &cfg); if (ret) { - VLOG_ERR("xsk_socket__create failed (%s) mode: %s qid: %d", + VLOG_ERR("xsk_socket__create failed (%s) mode: %s " + "use_need_wakeup: %s qid: %d", ovs_strerror(errno), xdpmode == XDP_COPY ? "SKB": "DRV", + use_need_wakeup ? "true" : "false", queue_id); free(xsk); return NULL; @@ -311,7 +368,8 @@ xsk_configure_socket(struct xsk_umem_info *umem, uint32_t ifindex, } static struct xsk_socket_info * -xsk_configure(int ifindex, int xdp_queue_id, int xdpmode) +xsk_configure(int ifindex, int xdp_queue_id, int xdpmode, + bool use_need_wakeup) { struct xsk_socket_info *xsk; struct xsk_umem_info *umem; @@ -334,7 +392,8 @@ xsk_configure(int ifindex, int xdp_queue_id, int xdpmode) VLOG_DBG("Allocated umem pool at 0x%"PRIxPTR, (uintptr_t) umem); - xsk = xsk_configure_socket(umem, ifindex, xdp_queue_id, xdpmode); + xsk = xsk_configure_socket(umem, ifindex, xdp_queue_id, xdpmode, + use_need_wakeup); if (!xsk) { /* Clean up umem and xpacket pool. */ if (xsk_umem__delete(umem->umem)) { @@ -365,9 +424,12 @@ xsk_configure_all(struct netdev *netdev) /* Configure each queue. */ for (i = 0; i < n_rxq; i++) { - VLOG_INFO("%s: configure queue %d mode %s", __func__, i, - dev->xdpmode == XDP_COPY ? "SKB" : "DRV"); - xsk_info = xsk_configure(ifindex, i, dev->xdpmode); + VLOG_DBG("%s: configure queue %d mode %s use_need_wakeup %s.", + netdev_get_name(netdev), i, + dev->xdpmode == XDP_COPY ? "SKB" : "DRV", + dev->use_need_wakeup ? "true" : "false"); + xsk_info = xsk_configure(ifindex, i, dev->xdpmode, + dev->use_need_wakeup); if (!xsk_info) { VLOG_ERR("Failed to create AF_XDP socket on queue %d.", i); dev->xsks[i] = NULL; @@ -459,6 +521,7 @@ netdev_afxdp_set_config(struct netdev *netdev, const struct smap *args, struct netdev_linux *dev = netdev_linux_cast(netdev); const char *str_xdpmode; int xdpmode, new_n_rxq; + bool need_wakeup; ovs_mutex_lock(&dev->mutex); new_n_rxq = MAX(smap_get_int(args, "n_rxq", NR_QUEUE), 1); @@ -481,10 +544,19 @@ netdev_afxdp_set_config(struct netdev *netdev, const struct smap *args, return EINVAL; } + need_wakeup = smap_get_bool(args, "use_need_wakeup", true); + if (need_wakeup) { +#ifndef HAVE_XDP_NEED_WAKEUP + VLOG_WARN("XDP need_wakeup is not supported in libbpf."); +#endif + } + if (dev->requested_n_rxq != new_n_rxq - || dev->requested_xdpmode != xdpmode) { + || dev->requested_xdpmode != xdpmode + || dev->requested_need_wakeup != need_wakeup) { dev->requested_n_rxq = new_n_rxq; dev->requested_xdpmode = xdpmode; + dev->requested_need_wakeup = need_wakeup; netdev_request_reconfigure(netdev); } ovs_mutex_unlock(&dev->mutex); @@ -499,7 +571,9 @@ netdev_afxdp_get_config(const struct netdev *netdev, struct smap *args) ovs_mutex_lock(&dev->mutex); smap_add_format(args, "n_rxq", "%d", netdev->n_rxq); smap_add_format(args, "xdpmode", "%s", - dev->xdpmode == XDP_ZEROCOPY ? "drv" : "skb"); + dev->xdpmode == XDP_ZEROCOPY ? "drv" : "skb"); + smap_add_format(args, "use_need_wakeup", "%s", + dev->use_need_wakeup ? "true" : "false"); ovs_mutex_unlock(&dev->mutex); return 0; } @@ -515,6 +589,7 @@ netdev_afxdp_reconfigure(struct netdev *netdev) if (netdev->n_rxq == dev->requested_n_rxq && dev->xdpmode == dev->requested_xdpmode + && dev->use_need_wakeup == dev->requested_need_wakeup && dev->xsks) { goto out; } @@ -538,6 +613,7 @@ netdev_afxdp_reconfigure(struct netdev *netdev) * when no device is in DRV mode. */ } + dev->use_need_wakeup = dev->requested_need_wakeup; err = xsk_configure_all(netdev); if (err) { @@ -660,6 +736,7 @@ netdev_afxdp_rxq_recv(struct netdev_rxq *rxq_, struct dp_packet_batch *batch, rcvd = xsk_ring_cons__peek(&xsk_info->rx, BATCH_SIZE, &idx_rx); if (!rcvd) { + xsk_rx_wakeup_if_needed(umem, netdev, rx->fd); return EAGAIN; } @@ -704,11 +781,15 @@ netdev_afxdp_rxq_recv(struct netdev_rxq *rxq_, struct dp_packet_batch *batch, } static inline int -kick_tx(struct xsk_socket_info *xsk_info, int xdpmode) +kick_tx(struct xsk_socket_info *xsk_info, int xdpmode, bool use_need_wakeup) { int ret, retries; static const int KERNEL_TX_BATCH_SIZE = 16; + if (use_need_wakeup && !xsk_tx_need_wakeup(xsk_info)) { + return 0; + } + /* In SKB_MODE packet transmission is synchronous, and the kernel xmits * only TX_BATCH_SIZE(16) packets for a single sendmsg syscall. * So, we have to kick the kernel (n_packets / 16) times to be sure that @@ -880,7 +961,7 @@ __netdev_afxdp_batch_send(struct netdev *netdev, int qid, &orig); COVERAGE_INC(afxdp_tx_full); afxdp_complete_tx(xsk_info); - kick_tx(xsk_info, dev->xdpmode); + kick_tx(xsk_info, dev->xdpmode, dev->use_need_wakeup); error = ENOMEM; goto out; } @@ -904,7 +985,7 @@ __netdev_afxdp_batch_send(struct netdev *netdev, int qid, xsk_ring_prod__submit(&xsk_info->tx, dp_packet_batch_size(batch)); xsk_info->outstanding_tx += dp_packet_batch_size(batch); - ret = kick_tx(xsk_info, dev->xdpmode); + ret = kick_tx(xsk_info, dev->xdpmode, dev->use_need_wakeup); if (OVS_UNLIKELY(ret)) { VLOG_WARN_RL(&rl, "%s: error sending AF_XDP packet: %s.", netdev_get_name(netdev), ovs_strerror(ret)); @@ -974,6 +1055,7 @@ netdev_afxdp_construct(struct netdev *netdev) dev->requested_n_rxq = NR_QUEUE; dev->requested_xdpmode = XDP_COPY; + dev->requested_need_wakeup = true; dev->xsks = NULL; dev->tx_locks = NULL; diff --git a/lib/netdev-linux-private.h b/lib/netdev-linux-private.h index a350be151147..c14f2fb81bb0 100644 --- a/lib/netdev-linux-private.h +++ b/lib/netdev-linux-private.h @@ -102,6 +102,8 @@ struct netdev_linux { int requested_n_rxq; int xdpmode; /* AF_XDP running mode: driver or skb. */ int requested_xdpmode; + bool use_need_wakeup; + bool requested_need_wakeup; struct ovs_spin *tx_locks; /* spin lock array for TX queues. */ #endif }; diff --git a/vswitchd/vswitch.xml b/vswitchd/vswitch.xml index 01304a5ed2c2..24d061891956 100644 --- a/vswitchd/vswitch.xml +++ b/vswitchd/vswitch.xml @@ -3122,6 +3122,18 @@ ovs-vsctl add-port br0 p0 -- set Interface p0 type=patch options:peer=p1 \ </p> </column> + <column name="options" key="use_need_wakeup" + type='{"type": "boolean"}'> + <p> + Specifies whether to use need_wakeup feature in afxdp netdev. + If enabled, OVS explicitly wakes up the kernel RX, using poll() + syscall and wakes up TX, using sendto() syscall. For physical + devices, this feature improves the performance by avoiding + unnecessary sendto syscalls. + Defaults is true. + </p> + </column> + <column name="options" key="vhost-server-path" type='{"type": "string"}'> <p>
The patch adds support for using need_wakeup flag in AF_XDP rings. A new option, use_need_wakeup, is added. When this option is used, it means that OVS has to explicitly wake up the kernel RX, using poll() syscall and wake up TX, using sendto() syscall. This feature improves the performance by avoiding unnecessary sendto syscalls for TX. For RX, instead of kernel always busy-spinning on fille queue, OVS wakes up the kernel RX processing when fill queue is replenished. The need_wakeup feature is merged into Linux kernel bpf-next tee with commit 77cd0d7b3f25 ("xsk: add support for need_wakeup flag in AF_XDP rings") and OVS enables it by default. Running the feature before this version causes xsk bind fails, please use options:use_need_wakeup=false to disable it. If users enable it but runs in an older version of libbpf, then the need_wakeup feature has no effect, and a warning message is logged. For virtual interface, it's better set use_need_wakeup=false, since the virtual device's AF_XDP xmit is synchronous: the sendto syscall enters kernel and process the TX packet on tx queue directly. On Intel Xeon E5-2620 v3 2.4GHz system, performance of physical port to physical port improves from 6.1Mpps to 7.3Mpps. Suggested-by: Ilya Maximets <i.maximets@ovn.org> Signed-off-by: William Tu <u9012063@gmail.com> --- v5: - address feedback from Ilya - update commit msg about kernel version using bpf-next tree - remove __func__, and use DBG in log_ - fix alignment - remove the kernel version requirement for need_wakeup, we can wait until tag is available v4: - move use_need_wakeup check inside xsk_rx_wakeup_if_needed v3: - add warning when user enables it but libbpf not support it - revise documentation v2: - address feedbacks from Ilya and Eelco - add options:use_need_wakeup, default to true - remove poll timeout=1sec, make poll() return immediately - naming change: rename to xsk_rx_wakeup_if_needing - fix indents and return value for errno --- Documentation/intro/install/afxdp.rst | 15 ++++- acinclude.m4 | 5 ++ lib/netdev-afxdp.c | 108 ++++++++++++++++++++++++++++++---- lib/netdev-linux-private.h | 2 + vswitchd/vswitch.xml | 12 ++++ 5 files changed, 126 insertions(+), 16 deletions(-)