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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Thank you. This did help. With the concurrency set to 16, I was able to get a max write speed of 1138 MB/s. Any ideas on how we can make that faster, though?
Ideally, we’d like to get to 1.5 GB/s.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Carl<o:p></o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> Liang Zhen [mailto:liang@whamcloud.com]
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<b>Sent:</b> Thursday, February 16, 2012 1:45 AM<br>
<b>To:</b> Barberi, Carl E<br>
<b>Cc:</b> 'lustre-discuss@lists.Lustre.org'<br>
<b>Subject:</b> EXTERNAL: Re: [Lustre-discuss] LNET Performance Issue<o:p></o:p></span></p>
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<p class="MsoNormal">Hi, I assume you are using "size=1M" for brw test right? performance could increase if you set "concurrency" while adding brw test, i.e: --concurrency=16<o:p></o:p></p>
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<p class="MsoNormal">Liang<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Feb 16, 2012, at 3:30 AM, Barberi, Carl E wrote:<o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">We are having issues with LNET performance over Infiniband. We have a configuration with a single MDT and six (6) OSTs. The Lustre client I am using to test is configured
to use 6 stripes (lfs setstripe -c 6 /mnt/lustre). When I perform a test using the following command:<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> dd if=/dev/zero of=/mnt/lustre/test.dat bs=1M count=2000<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">I typically get a write rate of about 815 MB/s, and we never exceed 848 MB/s. When I run obdfilter-survey, we easily get about 3-4GB/s write speed, but when I run a series
of lnet-selftests, the read and write rates range from 850MB/s – 875MB/s max. I have performed the following optimizations to increase the data rate:<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">On the Client:<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">lctl set_param osc.*.checksums=0<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">lctl set_param osc.*.max_dirty_mb=256<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">On the OSTs<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">lctl set_param obdfilter.*.writethrough_cache_enable=0<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">lctl set_param obdfilter.*.read_cache_enable=0<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">echo 4096 > /sys/block/<devices>/queue/nr_requests<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">I have also loaded the ib_sdp module, which also brought an increase in speed. However, we need to be able to record at no less than 1GB/s, which we cannot achieve right
now. Any thoughts on how I can optimize LNET, which clearly seems to be the bottleneck?<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">Thank you for any help you can provide,<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">Carl Barberi<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:13.5pt;font-family:"Helvetica","sans-serif"">_______________________________________________<br>
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