diff options
| -rw-r--r-- | tap.c | 28 |
1 files changed, 22 insertions, 6 deletions
@@ -75,12 +75,28 @@ CHECK_FRAME_LEN(L2_MAX_LEN_PASTA); CHECK_FRAME_LEN(L2_MAX_LEN_PASST); CHECK_FRAME_LEN(L2_MAX_LEN_VU); -#define TAP_MSGS \ - DIV_ROUND_UP(sizeof(pkt_buf), ETH_ZLEN - 2 * ETH_ALEN + sizeof(uint32_t)) +/* We try size the packet pools so that we can use a single batch for the entire + * packet buffer. This might be exceeded for vhost-user, though, which uses its + * own buffers rather than pkt_buf. + * + * This is just a tuning parameter, the code will work with slightly more + * overhead if it's incorrect. So, we estimate based on the minimum practical + * frame size - an empty UDP datagram - rather than the minimum theoretical + * frame size. + * + * FIXME: Profile to work out how big this actually needs to be to amortise + * per-batch syscall overheads + */ +#define TAP_MSGS_IP4 \ + DIV_ROUND_UP(sizeof(pkt_buf), \ + ETH_HLEN + sizeof(struct iphdr) + sizeof(struct udphdr)) +#define TAP_MSGS_IP6 \ + DIV_ROUND_UP(sizeof(pkt_buf), \ + ETH_HLEN + sizeof(struct ipv6hdr) + sizeof(struct udphdr)) /* IPv4 (plus ARP) and IPv6 message batches from tap/guest to IP handlers */ -static PACKET_POOL_NOINIT(pool_tap4, TAP_MSGS, pkt_buf); -static PACKET_POOL_NOINIT(pool_tap6, TAP_MSGS, pkt_buf); +static PACKET_POOL_NOINIT(pool_tap4, TAP_MSGS_IP4, pkt_buf); +static PACKET_POOL_NOINIT(pool_tap6, TAP_MSGS_IP6, pkt_buf); #define TAP_SEQS 128 /* Different L4 tuples in one batch */ #define FRAGMENT_MSG_RATE 10 /* # seconds between fragment warnings */ @@ -1418,8 +1434,8 @@ void tap_sock_update_pool(void *base, size_t size) { int i; - pool_tap4_storage = PACKET_INIT(pool_tap4, TAP_MSGS, base, size); - pool_tap6_storage = PACKET_INIT(pool_tap6, TAP_MSGS, base, size); + pool_tap4_storage = PACKET_INIT(pool_tap4, TAP_MSGS_IP4, base, size); + pool_tap6_storage = PACKET_INIT(pool_tap6, TAP_MSGS_IP6, base, size); for (i = 0; i < TAP_SEQS; i++) { tap4_l4[i].p = PACKET_INIT(pool_l4, UIO_MAXIOV, base, size); |