On Fri, Jul 11, 2014 at 01:05:30AM +0000, Wangkai (Kevin,C) wrote: > When used a tap as net driver for vm, if too many packets was delivered to > the > guest os via tap interface, the guest os will be blocked on io events for a > long > time, while tap driver was busying process packets.
Please tweak this description to explain clearly that the tap_send()
loop can execute for a very long time if more packets are received by
the host during tap_send().
It seems that the guest does not require the QEMU global mutex often
during virtio-net receive, otherwise the rx virtqueue would fill up and
tap_send() would return.
> diff --git a/net/tap.c b/net/tap.c
> index a40f7f0..df9a0eb 100644
> --- a/net/tap.c
> +++ b/net/tap.c
> @@ -189,6 +189,7 @@ static void tap_send(void *opaque)
> {
> TAPState *s = opaque;
> int size;
> + int pkt = 0;
>
> while (qemu_can_send_packet(&s->nc)) {
> uint8_t *buf = s->buf;
> @@ -210,6 +211,11 @@ static void tap_send(void *opaque)
> } else if (size < 0) {
> break;
> }
> +
> + /* limit io block time slice for 50 packets */
> + pkt++;
> + if (pkt >= 50)
> + break;
Please use scripts/checkpatch.pl to check coding style. QEMU always
uses curlies around if statement bodies, even when they are only one
line.
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