From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52262) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gUx1e-0003Zo-CD for qemu-devel@nongnu.org; Thu, 06 Dec 2018 12:01:23 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gUx1a-0006pQ-6z for qemu-devel@nongnu.org; Thu, 06 Dec 2018 12:01:21 -0500 Received: from mail-wr1-x442.google.com ([2a00:1450:4864:20::442]:42049) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1gUx1W-0006jT-FZ for qemu-devel@nongnu.org; Thu, 06 Dec 2018 12:01:16 -0500 Received: by mail-wr1-x442.google.com with SMTP id q18so1187080wrx.9 for ; Thu, 06 Dec 2018 09:01:10 -0800 (PST) From: Vincenzo Maffione Date: Thu, 6 Dec 2018 17:59:05 +0100 Message-Id: <20181206165907.23465-2-v.maffione@gmail.com> In-Reply-To: <20181206165907.23465-1-v.maffione@gmail.com> References: <20181206165907.23465-1-v.maffione@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Subject: [Qemu-devel] [PATCH v1 1/3] net: netmap: small improvements netmap_send() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: g.lettieri@iet.unipi.it, jasowang@redhat.com, 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 --- net/netmap.c | 31 +++++++++++++++++++------------ 1 file changed, 19 insertions(+), 12 deletions(-) diff --git a/net/netmap.c b/net/netmap.c index 2d11a8f4be..71a8122bdd 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; } -- 2.19.2