[Stgt-devel] Performance of SCST versus STGT

[Bart Van Assche]

On Jan 22, 2008 12:33 PM, Vladislav Bolkhovitin <vst at vlnb.net> wrote:
>
> What are the new SRPT/iSER numbers?

You can find the new performance numbers below. These are all numbers
for reading from the remote buffer cache, no actual disk reads were
performed. The read tests have been performed with dd, both for a
block size of 512 bytes and of 1 MB. The tests with small block size
learn more about latency, while the tests with large block size learn
more about the maximal possible throughput.

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

My conclusion from the above numbers: the performance difference
between STGT and SCST is small for a Gigabit Ethernet network. The
faster the network technology, the larger the difference between SCST
and STGT.

Bart.