[ofa-general] Expected RDMA performance

[Richard Frank]

Does it follow then that it's possible to get 1400 mbytes / sec out + 
1400 mbytes / sec in for total of 2800 mbytes rdma write + rdma read ?


Peter Kjellstrom wrote:
> On Thursday 18 October 2007, Chuck Hartley wrote:
> ...
>   
>> 8388608        5000            1342.12               1342.12
>> ------------------------------------------------------------------
>>
>> Is this typical RDMA performance?
>>     
>
> It's close to what I've seen on similar hw. ~1400 is what you can push through 
> the 8x pci-e of the intel 5000 chipset (confirmed by trying 4x pci-e which 
> has shown ~700).
>
>   
>> What is the maximum theoretical BW for 
>> DDR IB - 1525MB/sec?
>>     
>
> No, it's 20 Gbps on the wire and 8/10 encoded so 16 Gbps effective which is 
> 2000 MB/s (10-base) and 1907 MiB/s (2-base).
>
> On our system (with a different HCA) we see quite a difference with 
> snoop-filter off (bios option). With snoop off (our) application performance 
> goes up (not very suprising) but IB performance goes down (latency 0.4us 
> worse and bw ~1400->1200).
>
> /Peter
>   
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