<div dir="ltr">Werner, thanks for the answer.<br>Assuming we won't use bypass mode to access the local MPB, is there any software that tests the latency of accessing the local MPB. Our first-step goal is to measure the latency in this simple case and see that it is 45 core clock + 8 mesh clock as is stated in the graph or at least could be measured in clocks, not microseconds.<br>
Can you please relate to this picture: [<a href="https://docs.google.com/drawings/edit?id=1X-U10YjKvFQ22sdsKcNFnpHKVLyhR8_6YhJv6tiySUo&hl=en">https://docs.google.com/drawings/edit?id=1X-U10YjKvFQ22sdsKcNFnpHKVLyhR8_6YhJv6tiySUo&hl=en</a>]? Did anyone measured latency of those paths?<br>
Thanks again, KostaZ.<br><br><div class="gmail_quote">On Tue, Mar 1, 2011 at 5:53 PM, Haas, Werner <span dir="ltr"><<a href="mailto:werner.haas@intel.com">werner.haas@intel.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
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<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);" lang="EN-US">Konstantin,</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);" lang="EN-US"> </span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);" lang="EN-US">I work at Intel Labs so let me try answering the RCCE-related
part: The latency table reflects the numbers from looking at the actual
hardware, i.e. without taking software operation into account. The RCCE
round-trip times, however, were measured by running an actual application, i.e.
they rather reflect the efficiency of one particular communication algorithm
than hardware properties. I do not know the precise number but there are actually
several MPB accesses involved in passing data via RCCE. </span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);" lang="EN-US"> </span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);" lang="EN-US">Please also note that the bypass mode should _<i>not</i>_ be
used as we have a hardware bug which can lead to reading incorrect data.
Unfortunately this greatly reduces the benefit of using the on-die SRAM vs.
off-die DDR3.</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);" lang="EN-US"> </span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);" lang="EN-US">Best regards,</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);" lang="EN-US">Werner</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);" lang="EN-US"><br></span></p></div></div></blockquote></div><br></div>