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<p class="MsoNormal">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></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"> dd if=/dev/zero of=/mnt/lustre/test.dat bs=1M count=2000<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">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></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">On the Client:<o:p></o:p></p>
<p class="MsoNormal">lctl set_param osc.*.checksums=0<o:p></o:p></p>
<p class="MsoNormal">lctl set_param osc.*.max_dirty_mb=256<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">On the OSTs<o:p></o:p></p>
<p class="MsoNormal">lctl set_param obdfilter.*.writethrough_cache_enable=0<o:p></o:p></p>
<p class="MsoNormal">lctl set_param obdfilter.*.read_cache_enable=0<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">echo 4096 > /sys/block/<devices>/queue/nr_requests<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">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></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thank you for any help you can provide,<o:p></o:p></p>
<p class="MsoNormal">Carl Barberi<o:p></o:p></p>
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