On Jul 19, 2014, at 6:42 AM, Chris Ferebee via smartos-discuss
<[email protected]> wrote:
>
> I'm trying to debug a network performance issue.
>
> I have two servers running SmartOS (20140613T024634Z and 20140501T225642Z),
> one is a Supermicro dual Xeon E5649 (64 GB RAM) and the other is a dual Xeon
> E5-2620v2 (128 GB RAM). Each has an Intel X520-DA1 10GbE card, and they are
> both connected to 10GbE ports on a NetGear GS752TXS switch.
>
> The switch reports 10GbE links:
>
> 1/xg49 Enable 10G Full 10G Full Link Up
> Enable 1518 20:0C:C8:46:C8:3E 49 49
> 1/xg50 Enable 10G Full 10G Full Link Up
> Enable 1518 20:0C:C8:46:C8:3E 50 50
>
> as do both hosts:
>
> [root@90-e2-ba-00-2a-e2 ~]# dladm show-phys
> LINK MEDIA STATE SPEED DUPLEX DEVICE
> igb0 Ethernet down 0 half
> igb0
> igb1 Ethernet down 0 half
> igb1
> ixgbe0 Ethernet up 10000 full
> ixgbe0
>
> [root@00-1b-21-bf-e1-b4 ~]# dladm show-phys
> LINK MEDIA STATE SPEED DUPLEX DEVICE
> igb0 Ethernet down 0 half
> igb0
> ixgbe0 Ethernet up 10000 full
> ixgbe0
> igb1 Ethernet down 0 half
> igb1
>
> Per dladm show-linkprop, maxbw is not set on either of the net0 vnic
> interfaces.
>
> And yet, as measured via netcat, throughput is just below 1 Gbit/s:
>
> [root@90-e2-ba-00-2a-e2 ~]# time cat /zones/test/10gb | nc -v -v -n
> 192.168.168.5 8888
It's called "netcat" for a reason, why are you cat'ing into it?
time nc -v -v -n 192.168.168.5 8888 </zones/test/10gb
> Connection to 192.168.168.5 8888 port [tcp/*] succeeded!
>
> real 1m34.662s
> user 0m11.422s
> sys 1m53.957s
>
> (In this test, 10gb is a test file that is warm in RAM and transfers via dd
> to /dev/null at approx. 2.4 GByte/s.)
>
> What could be causing the slowdown, and how might I go about debugging this?
nc doesn't buffer, so a pipeline of data flowing through cat <-> nc <-> network
<-> nc <-> ??
is susceptible to delays at any stage rippling their latency back to the far
end. You're better
off testing performance with proper network performance testing tools like
iperf where such
things are not in the design.
-- richard
>
> FTR, disk throughput, while not an issue here, appears to be perfectly
> reasonable, approx. 900 MB/s read performance.
>
> Thanks for any pointers!
>
> Chris
>
>
>
>
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