Date: Tue, 03 Jan 2017 16:19:52 +0000 From: bugzilla-noreply@freebsd.org To: freebsd-amd64@FreeBSD.org Subject: [Bug 215737] [bhyve] utilizing virtio-net truncates jumbo frames at 4084 bytes length Message-ID: <bug-215737-6@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D215737 Bug ID: 215737 Summary: [bhyve] utilizing virtio-net truncates jumbo frames at 4084 bytes length Product: Base System Version: 11.0-STABLE Hardware: amd64 OS: Any Status: New Severity: Affects Some People Priority: --- Component: misc Assignee: freebsd-bugs@FreeBSD.org Reporter: bugzilla.freebsd@omnilan.de CC: freebsd-amd64@FreeBSD.org CC: freebsd-amd64@FreeBSD.org Steps to reproduce: 'ifconfig create vmnet0 mtu 9000' 'ifconfig brigde0 addm vmnet0' Set guest mtu to 9000 (which vtnet(4) claims to support). Now we can transceive frames up to 4084 bytes, which this flow from the guest's vtnet(4) interface demonstrates: 16:54:36.672709 00:a0:98:73:9f:42 > 96:07:e9:78:c6:ac, ethertype IPv4 (0x0800), length 4084: 172.21.35.1 > 172.21.35.32: ICMP echo request, id 56840, seq 0, length 4050 16:54:36.672791 96:07:e9:78:c6:ac > 00:a0:98:73:9f:42, ethertype IPv4 (0x0800), length 4084: 172.21.35.32 > 172.21.35.1: ICMP echo reply, id 56840, seq 0, length 4050 On the host this looks similar. Now with a payload size of 4043 instead of 4042 bytes, the reply never makes it through virtio-net: Host flow: 16:57:06.641382 00:a0:98:73:9f:42 > 96:07:e9:78:c6:ac, ethertype IPv4 (0x0800), length 4085: 172.21.35.1 > 172.21.35.32: ICMP echo request, id 27401, seq 0, length 4051 16:57:06.641399 96:07:e9:78:c6:ac > 00:a0:98:73:9f:42, ethertype IPv4 (0x0800), length 4085: 172.21.35.32 > 172.21.35.1: ICMP echo reply, id 27401, seq 0, length 4051 Guest flow: 16:57:06.642073 00:a0:98:73:9f:42 > 96:07:e9:78:c6:ac, ethertype IPv4 (0x0800), length 4085: 172.21.35.1 > 172.21.35.32: ICMP echo request, id 27401, seq 0, length 4051 16:57:06.642233 96:07:e9:78:c6:ac > 00:a0:98:73:9f:42, ethertype IPv4 (0x0800), length 4084: truncated-ip - 1 bytes missing! 172.21.35.32 > 172.21.35.1: ICMP echo reply, id 27401, seq 0, length 405 When using exactly the same setup, just replacing virtio-net with e1000 ('-s 5,virtio-net,vmnet0' with '-s 5,e1000,vmnet0'), jumbo frames do work as expected. Andrey V. Elsukov idea: > This looks like the problem with mbufs bigger than PAGE_SIZE. > Do you see some denied requests in the `netstat -m` output? Nope, there are no denied mbuf requests after sending icmp echo-request through virtio-net with all participants' MTU set to 9000: 0/0/0 requests for mbufs denied (mbufs/clusters/mbuf+clusters) 0/0/0 requests for jumbo clusters denied (4k/9k/16k) 0 requests for sfbufs denied --=20 You are receiving this mail because: You are on the CC list for the bug.=
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