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<p>Ez relevánsnak tűnik a crypto szempontjából és érdemes figyelembe
venni a szívások elkerülése végett.</p>
<p>Üdv.<br>
S<br>
</p>
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-------- Továbbított üzenet --------
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<th valign="BASELINE" nowrap="nowrap" align="RIGHT">Tárgy: </th>
<td>Re: [dpdk-users] Run-to-completion or Pipe-line for QAT
PMD in DPDK</td>
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<th valign="BASELINE" nowrap="nowrap" align="RIGHT">Dátum: </th>
<td>Fri, 18 Jan 2019 13:13:43 +0000</td>
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<th valign="BASELINE" nowrap="nowrap" align="RIGHT">Feladó:
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<td>Trahe, Fiona <a class="moz-txt-link-rfc2396E" href="mailto:fiona.trahe@intel.com"><fiona.trahe@intel.com></a></td>
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<th valign="BASELINE" nowrap="nowrap" align="RIGHT">Címzett:
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<td>Changchun Zhang <a class="moz-txt-link-rfc2396E" href="mailto:changchun.zhang@oracle.com"><changchun.zhang@oracle.com></a>,
<a class="moz-txt-link-abbreviated" href="mailto:users@dpdk.org">users@dpdk.org</a> <a class="moz-txt-link-rfc2396E" href="mailto:users@dpdk.org"><users@dpdk.org></a></td>
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<th valign="BASELINE" nowrap="nowrap" align="RIGHT">CC: </th>
<td>Trahe, Fiona <a class="moz-txt-link-rfc2396E" href="mailto:fiona.trahe@intel.com"><fiona.trahe@intel.com></a></td>
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<br>
Hi Alex,<br>
<br>
<blockquote type="cite">-----Original Message-----<br>
From: users [<a class="moz-txt-link-freetext" href="mailto:users-bounces@dpdk.org">mailto:users-bounces@dpdk.org</a>] On Behalf Of
Changchun Zhang<br>
Sent: Thursday, January 17, 2019 11:01 PM<br>
To: <a class="moz-txt-link-abbreviated" href="mailto:users@dpdk.org">users@dpdk.org</a><br>
Subject: [dpdk-users] Run-to-completion or Pipe-line for QAT PMD
in DPDK<br>
<br>
Hi,<br>
<br>
<br>
<br>
I have user question on using the QAT device in the DPDK.<br>
<br>
In the real design, after calling enqueuer_burst() on the
specified queue pair at one of the lcore,<br>
usually which one is usually done?<br>
<br>
1. should we do run-to-completion to call dequeuer_burst()
waiting for the device finishing the<br>
crypto operation,<br>
<br>
2. or should we do pipe-line, in which we return right after
enqueuer_burst() and release the CPU.<br>
And call dequeuer_burst() on other thread function?<br>
<br>
Option 1 is more like synchronous and can be seen on all the
DPDK crypto examples, while option 2 is<br>
asynchronous which I have never seen in any reference design if
I missed anything.<br>
</blockquote>
[Fiona] Option 2 is not possible with QAT - the dequeue must be
called in the same thread as the enqueue. This is<br>
optimised without atomics for best performance - if this is a
problem let us know. However best performance is not quite using
option 1 and not a synchronous blocking method. If you enqueue and
then go straight to dequeue, you're not getting the best advantage
from the<br>
cycles freed up by offloading. i.e. best to enqueue a burst, then
go do some other work, like maybe collecting more requests for
next enqueue or other processing, then dequeue. Take and process
whatever ops are dequeued - this<br>
will not necessarily match up with the number you've enqueued -
depends on how quickly you call the dequeue.<br>
Don't wait until all the enqueued ops are dequeued before
enqueuing the next batch.<br>
SO it's asynchronous. But in the same thread.<br>
You'll get best throughput when you keep the input filled up so
the device has operations to work on and<br>
regularly dequeue a burst. Dequeuing too often will waste cycles
in the overhead calling the API, dequeuing too<br>
slowly will cause the device to back up. Ideally tune for your
application to find the sweet spot in<br>
between these 2 extremes. </div>
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