On 11/20/2012 04:34 PM, Ben Greear wrote:
> On 11/20/2012 04:18 PM, Ben Greear wrote:

>>> 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?

Well..I stepped away for a bit, and when I came back, it is now working
very nicely.  Can do full 10G tx+tx on two ports, even with pktgen using
multi-skb at 0 (ie, no skb cloning).

And, bridging delay-emulator app of ours, which previously peaked at 6Gbps or 
so bi-directional
on i7/E3 systems runs 9GB+ even with full 1 second of one-way delay (ie, cold 
cache on the skbs).

So, I don't know why, aside from the VT-d, it was acting poorly earlier, but
all seems good now.  Maybe 'updatedb' or something similar was running and
I didn't notice....

I'll keep poking at this..and should have a 4-port 10G with gen-3 pcie
coming soon to play with.

Thanks,
Ben


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


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