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<p>A pull request has been opened for the initial support of traffic classes for libfabric. Please review as appropriate.
<o:p></o:p></p>
<p><a href="https://github.com/ofiwg/libfabric/pull/5148">https://github.com/ofiwg/libfabric/pull/5148</a><br>
<br>
This commit introduces the capability to select a traffic class when<br>
creating libfabric objects with the goal to allow applications to<br>
utilize traffic shaping mechanisms exposed to providers.<o:p></o:p></p>
<p>In this proposal, the fi_domain, fi_tx_attr, and fi_rx_attributes are<br>
modified to add the new fi_traffic_class structure to the structure definition.<br>
The fi_traffic_class structure provides a 'type' field, indicating the type of<br>
traffic class value that is represented in the 'value' field of the structure.<br>
Two different types of traffic class are presented with this commit; FI_TC_TYPE_LABEL,<br>
and FI_TC_TYPE_DSCP. Libfabric defines generalized traffic classes via community<br>
defined labels and expected behavior for those labels, which fall under the category<br>
of FI_TC_TYPE_LABEL. Providers may also define provider specific labels utilizing the<br>
most significant 32 bits of the value field. To provide applications with greater<br>
control over traffic class selection, this proposal exposes the ability to specify<br>
a specify DSCP value to be associated with libfabric objects, using the value field set<br>
to the DSCP value, and type set to FI_TC_TYPE_DSCP.<o:p></o:p></p>
<p>Additionally, to simplify the traffic class selection process, this commit introduces<br>
a heirarchal inheritance model with the fi_traffic_class structure. When an fi_domain<br>
is created, the application can choose to select a traffic class, or allow the provider<br>
to select a default traffic class. The traffic class associated with the domain is used<br>
as the default for all objects created within the domain. This allows an<br>
application to request a general traffic class for most traffic flows, while<br>
allowing the application to finely control traffic at the granularity of the tx context<br>
or rx context.<o:p></o:p></p>
<p>The original proposal to OFIWG did not include the rx context modification. However,<br>
multi-part data transfer operations such as rendezvous messaging benefit from the differentiation of<br>
request and response traffic shaping flows. The traffic class field in the rx attribute is<br>
only intended to apply to these multi-part data transfer operations and does not imply any<br>
relation with the tx attribute of a peer endpoint.<o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">-- Jim<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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