On 11/20/2012 04:18 PM, Ben Greear wrote:
> On 11/20/2012 03:59 PM, Alexander Duyck wrote:
>> On 11/20/2012 02:56 PM, Ben Greear wrote:
>>> We are trying out some new hardware, but it's not able to go above about 
>>> 4Gbps in each direction
>>> (using modified pktgen).  The two ixgbe ports are cabled to each other.
>>>
>>> Ethernet controller:
>>>
>>> 03:00.0 Ethernet controller: Intel Corporation 82599EB 10-Gigabit SFI/SFP+ 
>>> Network Connection (rev 01)
>>> 03:00.1 Ethernet controller: Intel Corporation 82599EB 10-Gigabit SFI/SFP+ 
>>> Network Connection (rev 01)
>>>
>>> CPU:
>>>
>>> Intel(R) Xeon(R) CPU E5-2643 0 @ 3.30GHz
>>>
>>> dmesg shows it is using 5GT/s:
>>>
>>> ixgbe 0000:03:00.0: (PCI Express:5.0GT/s:Width x8) 00:e0:ed:1e:d4:dc
>>>
>>>
>>> On similar setup (and same kernel) with i7 or e3 processor systems it runs
>>> right at 10Gbps bi-directional.
>>>
>>> Is the E5-2643 just not that fast of a processor, or should I expect
>>> better performance?
>>>
>>> Thanks,
>>> Ben
>>>
>>
>> What is the driver and kernel you are testing this with?
>
> kernel 3.5.7+, standard in-kernel driver.
>
>> Also, have you checked to make sure the feature set is comparable?  For
>> instance the E5 can support VT-d.  If that is enabled it can have a
>> negative impact on I/O performance due to extra locking overhead for
>> map/unmap calls on the host.
>
> I'll go poke around the BIOS and disable the VT-d if I can find it.

Wow, disabling VT-d gives a big improvement!

It now runs around 9.3Gbps bi-directional.  Still not as good as
our E3 or i7 systems, but it's at least closer.

Here's the new perf top

Samples: 24K of event 'cycles', Event count (approx.): 15591201274
  10.61%  [ixgbe]                       [k] ixgbe_poll
   6.76%  [pktgen]                      [k] pktgen_thread_worker
   6.40%  [kernel]                      [k] timekeeping_get_ns
   5.46%  [ixgbe]                       [k] ixgbe_xmit_frame_ring
   4.20%  libc-2.15.so                  [.] __memcpy_ssse3_back
   3.98%  [kernel]                      [k] do_raw_spin_unlock
   3.02%  [kernel]                      [k] skb_copy_bits
   2.99%  [kernel]                      [k] build_skb
   2.61%  perf-2510.map                 [.] 0x00007f73b2a28476
   2.56%  [kernel]                      [k] __netif_receive_skb


What CPU(s) do you suggest for high network bandwidth..hopefully
pci-e gen3 systems that can push beyond 2 10G NICs at full speed?


Thanks,
Ben

-- 
Ben Greear <[email protected]>
Candela Technologies Inc  http://www.candelatech.com


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