From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:34995) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gxCHH-0000VB-42 for qemu-devel@nongnu.org; Fri, 22 Feb 2019 09:58:17 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gxCF6-0007fa-A2 for qemu-devel@nongnu.org; Fri, 22 Feb 2019 09:56:01 -0500 Received: from mx1.redhat.com ([209.132.183.28]:34220) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gxCF5-0007Ck-SK for qemu-devel@nongnu.org; Fri, 22 Feb 2019 09:56:00 -0500 From: Jason Wang Date: Fri, 22 Feb 2019 22:55:18 +0800 Message-Id: <1550847320-25110-12-git-send-email-jasowang@redhat.com> In-Reply-To: <1550847320-25110-1-git-send-email-jasowang@redhat.com> References: <1550847320-25110-1-git-send-email-jasowang@redhat.com> Subject: [Qemu-devel] [PULL 11/13] net: netmap: small improvements netmap_send() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org, peter.maydell@linaro.org Cc: Vincenzo Maffione , Jason Wang From: Vincenzo Maffione This change improves the handling of incomplete multi-slot packets (e.g. with the NS_MOREFRAG set), by advancing ring->head only on complete packets. The ring->cur pointer is advanced in any case in order to acknowledge the kernel and move the wake-up point (thus avoiding repeated wake-ups). Also don't be verbose when incomplete packets are found. Signed-off-by: Vincenzo Maffione Signed-off-by: Jason Wang --- net/netmap.c | 31 +++++++++++++++++++------------ 1 file changed, 19 insertions(+), 12 deletions(-) diff --git a/net/netmap.c b/net/netmap.c index 2d11a8f..71a8122 100644 --- a/net/netmap.c +++ b/net/netmap.c @@ -272,39 +272,46 @@ static void netmap_send(void *opaque) { NetmapState *s = opaque; struct netmap_ring *ring = s->rx; + unsigned int tail = ring->tail; - /* Keep sending while there are available packets into the netmap + /* Keep sending while there are available slots in the netmap RX ring and the forwarding path towards the peer is open. */ - while (!nm_ring_empty(ring)) { - uint32_t i; + while (ring->head != tail) { + uint32_t i = ring->head; uint32_t idx; bool morefrag; int iovcnt = 0; int iovsize; + /* Get a (possibly multi-slot) packet. */ do { - i = ring->cur; idx = ring->slot[i].buf_idx; morefrag = (ring->slot[i].flags & NS_MOREFRAG); - s->iov[iovcnt].iov_base = (u_char *)NETMAP_BUF(ring, idx); + s->iov[iovcnt].iov_base = (void *)NETMAP_BUF(ring, idx); s->iov[iovcnt].iov_len = ring->slot[i].len; iovcnt++; + i = nm_ring_next(ring, i); + } while (i != tail && morefrag); - ring->cur = ring->head = nm_ring_next(ring, i); - } while (!nm_ring_empty(ring) && morefrag); + /* Advance ring->cur to tell the kernel that we have seen the slots. */ + ring->cur = i; - if (unlikely(nm_ring_empty(ring) && morefrag)) { - RD(5, "[netmap_send] ran out of slots, with a pending" - "incomplete packet\n"); + if (unlikely(morefrag)) { + /* This is a truncated packet, so we can stop without releasing the + * incomplete slots by updating ring->head. We will hopefully + * re-read the complete packet the next time we are called. */ + break; } iovsize = qemu_sendv_packet_async(&s->nc, s->iov, iovcnt, netmap_send_completed); + /* Release the slots to the kernel. */ + ring->head = i; + if (iovsize == 0) { /* The peer does not receive anymore. Packet is queued, stop - * reading from the backend until netmap_send_completed() - */ + * reading from the backend until netmap_send_completed(). */ netmap_read_poll(s, false); break; } -- 2.5.0