[OmniOS-discuss] Low latency networking

[Chris Nagele]

Hi Eric,

Richard had me run:

truss -dD ping -s 10.135.1.11

>From this result I can't seem to find anything useful. The longest
time is taken at the top:

0.0556  0.0000 write(1, "\n", 1)                               = 1
 0.9975  0.9419     Received signal #14, SIGALRM, in pollsys() [caught]
 0.9976  0.0001 pollsys(0x08047B50, 1, 0x00000000, 0x00000000)  Err#4 EINTR
 0.9976  0.0000 lwp_sigmask(SIG_SETMASK, 0x00002000, 0x00000000,
0x00000000, 0x00000000) = 0xFFBFFEFF [0xFFFFFFFF]
 0.9976  0.0000 sendto(3, "\b\0 AA3068A\001 lE51F P".., 64, 32768,
0x0807BA90, 16) = 64
 0.9977  0.0001 alarm(1)                                        = 0
 0.9977  0.0000 setcontext(0x08047660)
 0.9978  0.0001 pollsys(0x08047B50, 1, 0x00000000, 0x00000000)  = 1
 0.9978  0.0000 recvmsg(3, 0x08047CD0, 32768)                   = 84
 0.9978  0.0000 lwp_sigmask(SIG_SETMASK, 0x00002000, 0x00000000,
0x00000000, 0x00000000) = 0xFFBFFEFF [0xFFFFFFFF]
 0.9978  0.0000 lwp_sigmask(SIG_SETMASK, 0x00000000, 0x00000000,
0x00000000, 0x00000000) = 0xFFBFFEFF [0xFFFFFFFF]
64 bytes from 10.135.1.11:  0.9979       0.0001 write(1, " 6 4   b y t
e s   f r o".., 27)      = 27
icmp_seq=1.  0.9979      0.0000 write(1, " i c m p _ s e q = 1 .  ",
12)        = 12
time=0.225 ms 0.9980     0.0001 write(1, " t i m e = 0 . 2 2 5   m"..,
13)      = 13

Looking at snoop, I see the following:

 18.34001  10.135.1.10 -> debian-host  length:   98  ICMP Echo request
(ID: 1780 Sequence number: 5)
 18.34019  debian-host -> 10.135.1.10  length:   98  ICMP Echo reply
(ID: 1780 Sequence number: 5)
 18.34641  debian-host -> *            length:   60  ARP C Who is
10.135.1.10, 10.135.1.10 ?
 18.34643  10.135.1.10 -> debian-host  length:   42  ARP R
10.135.1.10, 10.135.1.10 is 90:e2:ba:f:ce:ec
 19.34000  10.135.1.10 -> debian-host  length:   98  ICMP Echo request
(ID: 1780 Sequence number: 6)
 19.34018  debian-host -> 10.135.1.10  length:   98  ICMP Echo reply
(ID: 1780 Sequence number: 6)
 20.33998  10.135.1.10 -> debian-host  length:   98  ICMP Echo request
(ID: 1780 Sequence number: 7)
 20.34015  debian-host -> 10.135.1.10  length:   98  ICMP Echo reply
(ID: 1780 Sequence number: 7)

Which all looks pretty normal as well. I might give superping.d a try
as well (http://www.c0t0d0s0.org/archives/7479-Dont-misuse-ping!.html).

Let me know if you have any other ideas.

Thanks,
Chris


On Mon, Aug 6, 2012 at 10:06 AM, Eric Sproul <esproul at omniti.com> wrote:
> On Sun, Aug 5, 2012 at 8:07 PM, Chris Nagele <nagele at wildbit.com> wrote:
>> For some reason though, ping times from OmniOS to Debian are still
>> much slower, above 0.2ms. I know it is nit picking, but we invested in
>> 10g for lower latency, so I am trying to get the most out of it. From
>> Debian to OmniOS I get about 0.08ms still.
>
> Hi Chris,
> It'd be great to see some tcpdumps of this traffic.  The most curious
> thing to me is that you see differences in RTT between Debian and
> OmniOS systems just by switching sender and receiver.  Perhaps there's
> something about the payload of a typical ping packet between the
> systems.
>
> Eric
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