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<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Greetings,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Hopefully the subject says it all…<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I’ve stumbled on a performance issue with the OFED ib_srp
driver. Here is the configuration. I am testing with a DDN 9550 and
a single host system. The systems are connected by two SDR links.
On the host side there is a dual port (DDR) card. On the DDN side, both
lines go into a single singlet (even though it is a couplet). The lines
go into two distinct cards on the DDN side (if you are familiar with the
layout). The testing used OFED 1.2.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Now for the tests… If I run a single stream test
I’m seeing good result with over 700 MB/s. These tests are run
using sg_dd with the directio flag. If I run two concurrent streams
against two LUNs that are each presented over a single port on the DDN (and
therefore accessed by a single port on the host side), the aggregate
performance drop to around 120 MB/s (60 MB/s per stream).<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Just to confirm it isn’t a problem on the DDN side, I
repeated these tests with the IBGD driver. There I consistently saw about
600-650 MB/s on the port regardless of the number of LUNs I tested with.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Any ideas on what the problem is? Also, if this doesn’t
make sense, let me know and I will try to clarify further.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Thanks,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>--Shane Canon<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>--</span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>R. Shane Canon</span></font><o:p></o:p></p>
<p class=MsoNormal><st1:place w:st="on"><st1:PlaceName w:st="on"><font size=2
face=Arial><span style='font-size:10.0pt;font-family:Arial'>National</span></font></st1:PlaceName><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'> <st1:PlaceType
w:st="on">Center</st1:PlaceType></span></font></st1:place><font size=2
face=Arial><span style='font-size:10.0pt;font-family:Arial'> for Computational
Science</span></font><o:p></o:p></p>
<p class=MsoNormal><st1:City w:st="on"><st1:place w:st="on"><font size=2
face=Arial><span style='font-size:10.0pt;font-family:Arial'>Oak Ridge</span></font></st1:place></st1:City><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'> National
Laboratory</span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>canonrs@ornl.gov</span></font><o:p></o:p></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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