On Sun, 2010-08-22 at 09:39 +0200, Bart Van Assche wrote:

On Sat, Aug 21, 2010 at 10:43 PM, James Bottomley
[off-list ref] wrote:

quoted

On Sat, 2010-08-21 at 22:42 +0400, Vladislav Bolkhovitin wrote:

quoted

[ ... ]

You forgot to mention one small thing. You are going to (re)use current
STGT interface for user space backend, which in 5 years of being
mainline has not gained any noticeable interest, because it is
fundamentally slow.

That's not exactly what the results of a speed comparison one of your
people did said, now is it?  The results were actually not much
difference on line speeds up to GigE.

[ ... ]

I assume that you are referring to this message:
http://lkml.org/lkml/2008/1/29/387 ? You might have missed the reply
that was posted by Roland Dreier, a highly regarded kernel maintainer
and InfiniBand expert (http://lkml.org/lkml/2008/1/29/402):

"Maybe I'm all wet, but I think iSER vs. SRP should be roughly
comparable.  The exact formatting of various messages etc. is
different but the data path using RDMA is pretty much identical.  So
the big difference between STGT iSER and SCST SRP hints at some big
difference in the efficiency of the two implementations."

So the phrase "up to GigE" was deliberately in the above to exclude the
disputed infiniband results.  I'm not really interested in re-opening
the arguments over how to interpret those results.  The fact that SCST
and STGT were on par up to 1GbE is enough to refute the contention that
STGT is "fundamentally slow".

James 

Furthermore, I would like to clarify that Vlad hasn't asked me to
start working on the SCST project but that I selected the SCST project
myself after an extensive stability and performance comparison of four
existing open source storage target projects.

Bart.
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