Hi Darrell:
Sorry for my late reply. Yes, the two VMs under test are on same compute
node , and pkts rx/tx via vhost user type port.Firstly if I don't configure
meter table, then Iperf TCP bandwidth result From VM1 to VM2 is around 5Gbps,
then I set the meter entry and constraint the rate, and the deviation is larger
than I throught.
I guess the recalculation of l4 checksum during conntrack would impact the
actual rate?
Thank you
Timo
txfh2007 <[email protected]>
Ben Pfaff <[email protected]>; ovs-discuss <[email protected]>
Re: [ovs-discuss] Re：Re： [HELP] Question about icmp pkt marked Invalid by
userspace conntrack
Hi Timo
I read thru this thread to get more context on what you are doing; you have a
base OVS-DPDK
use case and are measuring VM to VM performance across 2 compute nodes. You are
probably using
vhost-user-client ports ? Pls correct me if I am wrong.
In this case, "per direction" you have one rx virtual interface to handle in
OVS; there will be a tradeoff b/w
checksum validation security and performance.
JTBC, in terms of your measurements, how did you arrive at the 5Gbps -
instrumented code or otherwise ?.
(I can verify that later when I have a setup).
Darrell
On Thu, Oct 31, 2019 at 9:23 AM Darrell Ball <[email protected]> wrote:
On Thu, Oct 31, 2019 at 3:04 AM txfh2007 via discuss
<[email protected]> wrote:
Hi Ben && Darrell：
This patch works, but after merging this patch I have found the iperf
throughout decrease from 5Gbps+ to 500Mbps.
what is the 5Gbps number ? Is that the number with marking all packets as
invalid in initial sanity checks ?
Typically one wants to offload checksum checks. The code checks whether that
has been done and skips
doing it in software; can you verify that you have the capability and are using
it ?
Skipping checksum checks reduces security, of course, but it can be added if
there is a common case of
not being able to offload checksumming.
I guess maybe we should add a switch to turn off layer4 checksum validation
when doing userspace conntrack ? I have found for kernel conntrack, there is a
related button named "nf_conntrack_checksum" .
Any advice?
Thank you !
------------------------------------------------------------------
：Ben Pfaff <[email protected]>
：ovs-discuss <[email protected]>
：Re：Re：[ovs-discuss] [HELP] Question about icmp pkt marked Invalid by userspace
conntrack
Hi Ben && Darrell：
Thanks, this patch works! Now the issue seems fixed
Timo
Re: Re：[ovs-discuss] [HELP] Question about icmp pkt marked Invalid by userspace
conntrack
I see.
It sounds like Darrell pointed out the solution, but please let me know
if it did not help.
On Fri, Oct 11, 2019 at 08:57:58AM +0800, txfh2007 wrote:
> Hi Ben:
>
> I just found the GCC_UNALIGNED_ACCESSORS error during gdb trace and not
> sure this is a misaligned error or others. What I can confirm is during
> "extract_l4" of this icmp reply packet, when we do "check_l4_icmp", the
> unaligned error emits and the "extract_l4" returned false. So this packet be
> marked as ct_state=invalid.
>
> Thank you for your help.
>
> Timo
>
> Topic：Re: [ovs-discuss] [HELP] Question about icmp pkt marked Invalid by
> userspace conntrack
>
>
> It's very surprising.
>
> Are you using a RISC architecture that insists on aligned accesses? On
> the other hand, if you are using x86-64 or some other architecture that
> ordinarily does not care, are you sure that this is about a misaligned
> access (it is more likely to simply be a bad pointer)?
>
> On Thu, Oct 10, 2019 at 10:50:33PM +0800, txfh2007 via discuss wrote:
> >
> > Hi all:
> > I was using OVS-DPDK(version 2.10-1), and I have found pinging between
> > two VMs on different compute nodes failed. I have checked my env and found
> > there is one node's NIC cannot strip CRC of a frame, the other node's NIC
> > is normal(I mean it can strip CRC ). And the reason of ping fail is the
> > icmp reply pkt (from node whose NIC cannot strip CRC) is marked as invalid
> > . So the icmp request From Node A is 64 bytes， but the icmp reply From Node
> > B is 68 bytes(with 4 bytes CRC). And when doing "check_l4_icmp", when we
> > call csum task(in lib/csum.c). Gcc emits unaligned accessor error. The
> > backtrace is as below:
> >
> > I just want to confirm if this phenomenon is reasonable?
> >
> > Many thanks
> >
> > Timo
> >
> >
> > get_unaligned_be16 (p=0x7f2ad0b1ed5c) at lib/unaligned.h:89
> > 89 GCC_UNALIGNED_ACCESSORS(ovs_be16, be16);
> > (gdb) bt
> > #0 get_unaligned_be16 (p=0x7f2ad0b1ed5c) at lib/unaligned.h:89
> > #1 0x000000000075a584 in csum_continue (partial=0, data_=0x7f2ad0b1ed5c,
> > n=68) at lib/csum.c:46
> > #2 0x000000000075a552 in csum (data=0x7f2ad0b1ed5c, n=68) at lib/csum.c:33
> > #3 0x00000000008ddf18 in check_l4_icmp (data=0x7f2ad0b1ed5c, size=68,
> > validate_checksum=true) at lib/conntrack.c:1638
> > #4 0x00000000008de650 in extract_l4 (key=0x7f32a20df120,
> > data=0x7f2ad0b1ed5c, size=68, related=0x7f32a20df15d, l3=0x7f2ad0b1ed48,
> > validate_checksum=true) at lib/conntrack.c:1888
> > #5 0x00000000008de90d in conn_key_extract (ct=0x7f32b42a2d98,
> > pkt=0x7f2ad0b1e9c0, dl_type=8, ctx=0x7f32a20df120, zone=4)
> > at lib/conntrack.c:1973
> > #6 0x00000000008dd49c in conntrack_execute (ct=0x7f32b42a2d98,
> > pkt_batch=0x7f32a20e08b0, dl_type=8, force=false, commit=false,
> > zone=4, setmark=0x0, setlabel=0x0, tp_src=0, tp_dst=0, helper=0x0,
> > nat_action_info=0x0, now=5395897849) at lib/conntrack.c:1318
> > #7 0x000000000076d651 in dp_execute_cb (aux_=0x7f32a20dfb00,
> > packets_=0x7f32a20e08b0, a=0x7f32a20e0ac8, should_steal=false)
> > at lib/dpif-netdev.c:6711
> > #8 0x00000000007b2d49 in odp_execute_actions (dp=0x7f32a20dfb00,
> > batch=0x7f32a20e08b0, steal=true, actions=0x7f32a20e0ac8,
> > actions_len=20, dp_execute_action=0x76ca60 <dp_execute_cb>) at
> > lib/odp-execute.c:726
> > #9 0x000000000076d71b in dp_netdev_execute_actions (pmd=0x7f2a6e1ce010,
> > packets=0x7f32a20e08b0, should_steal=true,
> > flow=0x7f32a20dfb60, actions=0x7f32a20e0ac8, actions_len=20) at
> > lib/dpif-netdev.c:6754
> > #10 0x000000000076b900 in handle_packet_upcall (pmd=0x7f2a6e1ce010,
> > packet=0x7f2ad0b1e9c0, key=0x7f32a20e1100,
> > actions=0x7f32a20e0a40, put_actions=0x7f32a20e0a80) at
> > lib/dpif-netdev.c:6056
> > #11 0x000000000076bdf0 in fast_path_processing (pmd=0x7f2a6e1ce010,
> > packets_=0x7f32a20e2b60, keys=0x7f32a20e10c0,
> > batches=0x7f32a20e0f90, n_batches=0x7f32a20e13c0, in_port=15) at
> > lib/dpif-netdev.c:6153
> > #12 0x000000000076c3df in dp_netdev_input__ (pmd=0x7f2a6e1ce010,
> > packets=0x7f32a20e2b60, md_is_valid=true, port_no=0)
> > at lib/dpif-netdev.c:6230
> > #13 0x000000000076c4d4 in dp_netdev_recirculate (pmd=0x7f2a6e1ce010,
> > packets=0x7f32a20e2b60) at lib/dpif-netdev.c:6265
> > #14 0x000000000076ceae in dp_execute_cb (aux_=0x7f32a20e1db0,
> > packets_=0x7f32a20e2b60, a=0x7f32a20e2d78, should_steal=true)
> >
> >
> > _______________________________________________
> > discuss mailing list
> > [email protected]
> > https://mail.openvswitch.org/mailman/listinfo/ovs-discuss
>
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