From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christian Ehrhardt Date: Tue, 25 Mar 2008 13:45:47 +0000 Subject: [kvm-ppc-devel] virtio network traffic issues Message-Id: <47E9020B.3080705@linux.vnet.ibm.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable To: kvm-ppc@vger.kernel.org Hi, I analyzed the network traffic to get a feeling where our bug may be locate= d. I summarize some things I think I see in that data Environment: 192.168.1.2 =3D nfs host 192.168.1.3 =3D ppc host 192.168.1.4 =3D ppc host 2nd network interface (not active, but bridged to = tap) 192.168.1.10 =3D ppc vkvm guest - configured via dhcp (working) time 0-25: host nfs and telnet time ~25: DHCP discover from kvm guest + offer answer from dhcp server after that there are arp requests for the nfs host which are answere= d correctly the guest starts to get a portmap response for nfs and mounts the nf= s share Then the guest does some nfs getattr, statfs calls followed by some = larger read calls (fragmented) The read calls are single packets while the reply (the data) is frag= mented In the wireshark protocol we even see that it accesses 1st dev/conso= le and then /sbin/init (this is where the reads go to) This continues to ld.1.so and other libs which are read via nfs (res= ponse looks good) packet 350 is retransmitted as packet 356 - there is no visible error - so = it must have been a ?timeout? then we get more retransmissions of that request ( there are replies to the= se requests all the time - does the guest not "see them"?) packet 365 is then a reply to a getattr call before =3D> it looks as if after #353 no packet was actually received by the guest after that only timeouts retransmits and unanswered arp requests are seen packet 368-385 have some kind of arp flood asking for 192.168.1.10 (the kvm= guest) but there is no reply to that too First these are direct arp requests then broadcasts - this looks (as descri= bed above) as if after packet 353 no packet is recieved by the guest The rest is my telnet connection aborting the kvm guest and some host->nfs = server traffic not interesting for us: Summary: =3D> from one not yet defined point our guest seems to receive absolutely n= othing =3D> when the guest is hanging it sends nfs requests which are seen externa= lly, but it does not seem to get the respones =3D> the arp requests for the guest are repeated - maybe we can add some ve= ry verbose debug in the guest virtio code and activate it when we see that = it is already hanging =3D> ideas: - maybe some buffer/memory runs out and so incoming packets won't be rece= ived anymore=20 - we break something in virtio / incoming interrupts (or maybe a lock) an= d from that point no receive is possible I'll continue on that and keep you informed --=20 Gr=FCsse / regards,=20 Christian Ehrhardt IBM Linux Technology Center, Open Virtualization ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ kvm-ppc-devel mailing list kvm-ppc-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-ppc-devel