Ping.... Thanks Zhenyu Gao
2017-07-17 10:39 GMT+08:00 Zhenyu Gao <[email protected]>: > Sendmmsg can reduce cpu cycles in sending packets to kernel. > Replace sendmsg with sendmmsg in function netdev_linux_send to send > batch packets if sendmmsg is available. > > If kernel side doesn't support sendmmsg, will fallback to sendmsg. > > netserver > |------------| > | | > | container | > |----veth----| > | > | |------------| > |---veth-| dpdk-ovs | netperf > | | |--------------| > |----dpdk----| | bare-metal | > | |--------------| > | | > | | > pnic-----------pnic > > Netperf was consumed to test the performance: > > 1)cmd:netperf -H remote-container -t UDP_STREAM -l 60 -- -m 1400 > result: netserver received 2383.21Mb(sendmsg)/2551.64Mb(sendmmsg) > > 2)cmd:netperf -H remote-container -t UDP_STREAM -l 60 -- -m 60 > result: netserver received 109.72Mb(sendmsg)/115.18Mb(sendmmsg) > > Sendmmsg show about 6% improvement in netperf UDP testing. > > Signed-off-by: Zhenyu Gao <[email protected]> > --- > lib/netdev-linux.c | 85 ++++++++++++++++++++++++++++++ > +++++++++--------------- > 1 file changed, 62 insertions(+), 23 deletions(-) > > diff --git a/lib/netdev-linux.c b/lib/netdev-linux.c > index e1d8701..d991d05 100644 > --- a/lib/netdev-linux.c > +++ b/lib/netdev-linux.c > @@ -1182,6 +1182,54 @@ netdev_linux_rxq_drain(struct netdev_rxq *rxq_) > } > } > > +static inline int > +netdev_linux_sock_batch_send(int sock, struct msghdr *msg, > + struct dp_packet_batch *batch) > +{ > + int error = 0; > + ssize_t retval; > + uint32_t resend_idx = 0; > + struct mmsghdr *mmsg; > + struct iovec *iov; > + > + mmsg = xmalloc(sizeof(*mmsg) * batch->count); > + iov = xmalloc(sizeof(*iov) * batch->count); > + > + for (int i = 0; i < batch->count; i++) { > + const void *data = dp_packet_data(batch->packets[i]); > + size_t size = dp_packet_size(batch->packets[i]); > + > + /* Truncate the packet if it is configured. */ > + size -= dp_packet_get_cutlen(batch->packets[i]); > + > + iov[i].iov_base = CONST_CAST(void *, data); > + iov[i].iov_len = size; > + mmsg[i].msg_hdr = *msg; > + mmsg[i].msg_hdr.msg_iov = &iov[i]; > + } > + > +resend_batch: > + retval = sendmmsg(sock, mmsg + resend_idx, > + batch->count - resend_idx, 0); > + if (retval < 0) { > + if (errno == EINTR) { > + goto resend_batch; > + } > + /* The Linux AF_PACKET implementation never blocks waiting for > + * room for packets, instead returning ENOBUFS. Translate this > + * into EAGAIN for the caller. */ > + error = errno == ENOBUFS ? EAGAIN : errno; > + } else if (retval != batch->count - resend_idx) { > + /* Send remain packets again. */ > + resend_idx += retval; > + goto resend_batch; > + } > + > + free(mmsg); > + free(iov); > + return error; > +} > + > /* Sends 'buffer' on 'netdev'. Returns 0 if successful, otherwise a > positive > * errno value. Returns EAGAIN without blocking if the packet cannot be > queued > * immediately. Returns EMSGSIZE if a partial packet was transmitted or > if > @@ -1226,6 +1274,9 @@ netdev_linux_send(struct netdev *netdev_, int qid > OVS_UNUSED, > msg.msg_control = NULL; > msg.msg_controllen = 0; > msg.msg_flags = 0; > + > + error = netdev_linux_sock_batch_send(sock, &msg, batch); > + goto check_error; > } > > /* 'i' is incremented only if there's no error */ > @@ -1236,34 +1287,21 @@ netdev_linux_send(struct netdev *netdev_, int qid > OVS_UNUSED, > > /* Truncate the packet if it is configured. */ > size -= dp_packet_get_cutlen(batch->packets[i]); > + /* Use the tap fd to send to this device. This is essential for > + * tap devices, because packets sent to a tap device with an > + * AF_PACKET socket will loop back to be *received* again on the > + * tap device. This doesn't occur on other interface types > + * because we attach a socket filter to the rx socket. */ > + struct netdev_linux *netdev = netdev_linux_cast(netdev_); > > - if (!is_tap_netdev(netdev_)) { > - /* Use our AF_PACKET socket to send to this device. */ > - struct iovec iov; > - > - iov.iov_base = CONST_CAST(void *, data); > - iov.iov_len = size; > - > - msg.msg_iov = &iov; > - > - retval = sendmsg(sock, &msg, 0); > - } else { > - /* Use the tap fd to send to this device. This is essential > for > - * tap devices, because packets sent to a tap device with an > - * AF_PACKET socket will loop back to be *received* again on > the > - * tap device. This doesn't occur on other interface types > - * because we attach a socket filter to the rx socket. */ > - struct netdev_linux *netdev = netdev_linux_cast(netdev_); > - > - retval = write(netdev->tap_fd, data, size); > - } > + retval = write(netdev->tap_fd, data, size); > > if (retval < 0) { > if (errno == EINTR) { > /* The send was interrupted by a signal. Retry the > packet by > * continuing without incrementing 'i'.*/ > continue; > - } else if (errno == EIO && is_tap_netdev(netdev_)) { > + } else if (errno == EIO) { > /* The Linux tap driver returns EIO if the device is not > up. > * From the OVS side this is not an error, so ignore it. > */ > } else { > @@ -1285,9 +1323,10 @@ netdev_linux_send(struct netdev *netdev_, int qid > OVS_UNUSED, > i++; > } > > +check_error: > if (error && error != EAGAIN) { > - VLOG_WARN_RL(&rl, "error sending Ethernet packet on %s: %s", > - netdev_get_name(netdev_), ovs_strerror(error)); > + VLOG_WARN_RL(&rl, "error sending Ethernet packet on %s: %s", > + netdev_get_name(netdev_), ovs_strerror(error)); > } > > free_batch: > -- > 1.8.3.1 > > _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
