Bart Van Assche wrote:
> On Jan 24, 2008 8:06 AM, Robin Humble <[EMAIL PROTECTED]> wrote:
> 
>>On Tue, Jan 22, 2008 at 01:32:08PM +0100, Bart Van Assche wrote:
>>
>>>.............................................................................................
>>>.                           .   STGT read     SCST read    .    STGT read    
>>>  SCST read    .
>>>.                           .  performance   performance   .   performance   
>>> performance   .
>>>.                           .  (0.5K, MB/s)  (0.5K, MB/s)  .   (1 MB >MB/s)  
>>> (1 MB, MB/s)  .
>>>.............................................................................................
>>>. Ethernet (1 Gb/s network) .      77             78       .         77      
>>>      89       .
>>>. IPoIB    (8 Gb/s network) .     163            185       .        201      
>>>     239       .
>>>. iSER     (8 Gb/s network) .     250            N/A       .        360      
>>>     N/A       .
>>>. SRP      (8 Gb/s network) .     N/A            421       .        N/A      
>>>     683       .
>>>............................................................................................
>>
> 
> Results with /dev/ram0 configured as backing store on the target (buffered 
> I/O):
>                     Read          Write             Read          Write
>                   performance   performance       performance   performance
>                   (0.5K, MB/s)  (0.5K, MB/s)      (1 MB, MB/s)  (1 MB, MB/s)
> STGT + iSER           250          48                 349          781
> SCST + SRP            411          66                 659          746

Ib_rdma_bw now reports 933 MB/s on the same system, correct? Those 
~250MB/s difference is what you will gain with zero-copy IO implemented 
and what STGT with the current architecture has no chance to achieve.

> Results with /dev/ram0 configured as backing store on the target (direct I/O):
>                     Read          Write             Read          Write
>                   performance   performance       performance   performance
>                   (0.5K, MB/s)  (0.5K, MB/s)      (1 MB, MB/s)  (1 MB, MB/s)
> STGT + iSER             7.9         9.8               589          647
> SCST + SRP             12.3         9.7               811          794
> 
> Bart.
> 

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