Re: Performance of SCST versus STGT

[Vladislav Bolkhovitin]

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       .
............................................................................................

how are write speeds with SCST SRP?
for some kernels and tests tgt writes at >2x the read speed.

Robin,

There is a fundamental difference between regular dd-like reads and 
writes: reads are sync, i.e. latency sensitive, but writes are async, 
i.e. latency insensitive. You should use O_DIRECT dd writes for the fair 
comparison.

Vlad
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