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<TITLE>RDMA vs Shared Memory</TITLE>
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<P><SPAN LANG="en-us"><FONT SIZE=2 FACE="Arial">Hello,</FONT></SPAN>
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<P><SPAN LANG="en-us"><FONT SIZE=2 FACE="Arial">I was trying to find out fastest IPC where data source and sink run on the same host on SLES 10, running ConnectX and OFED 1.3.0. It seems RDMA is performing much better than shared memory. </FONT></SPAN></P>
<P><SPAN LANG="en-us"><FONT SIZE=2 FACE="Arial">Mode Latency (microsecs) Throughput </FONT></SPAN>
<BR><SPAN LANG="en-us"><FONT SIZE=2 FACE="Arial">------- ----------------------------- ----------------</FONT></SPAN>
<BR><SPAN LANG="en-us"><FONT SIZE=2 FACE="Arial">SHM 20 (32 bytes) 17 Mbps </FONT></SPAN>
<BR><SPAN LANG="en-us"><FONT SIZE=2 FACE="Arial">RDMA 1.07 (32 bytes) 1.2 Gbps</FONT></SPAN>
<BR><SPAN LANG="en-us"><FONT SIZE=2 FACE="Arial">SHM 70 (32k) 5.2 Gbps</FONT></SPAN>
<BR><SPAN LANG="en-us"><FONT SIZE=2 FACE="Arial">RDMA 30 (32k) 8.5 Gbps</FONT></SPAN>
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<P><SPAN LANG="en-us"><FONT SIZE=2 FACE="Arial">Can someone explain why RDMA's giving better performance on the same host? Is it only kernel bypass and zcopy? </FONT></SPAN>
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<P><SPAN LANG="en-us"><FONT SIZE=2 FACE="Arial">Thanks</FONT></SPAN>
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<P><SPAN LANG="en-us"><FONT SIZE=2 FACE="Arial">Rajib </FONT></SPAN>
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