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<p><font face="monospace">Hi,</font></p>
<p><font face="monospace">I am looking into getting the hardware
timestamp of when a packet is received by the NIC inside of my
DPDK program. In a regular program I can get the timestamp the
packet is received by the NIC and the kernel using </font><font
face="monospace">SO_TIMESTAMPING [0]. Is there a way to get this
timestamp in dpdk?<br>
</font></p>
<p><font face="monospace">What I found when looking for this, it
looks like `mbuf->timestamp` was deprecated [1] and was
replaced in this [2] example by `<span class="blob-code-inner
blob-code-marker js-code-nav-pass " data-code-marker="+"><span
class="pl-s1">rte_mbuf_timestamp_t` (in </span></span><span
class="blob-code-inner blob-code-marker js-code-nav-pass "
data-code-marker="+"><span class="pl-s1"><span
class="blob-code-inner blob-code-marker js-code-nav-pass "
data-code-marker="+"><span class="pl-en">hwts_field)</span></span>.
When looking at the values I get from `</span></span><span
class="blob-code-inner blob-code-marker js-code-nav-pass "
data-code-marker="+"><span class="pl-en">hwts_field` it cycles
around 50244192 though, going up _and_ down?</span></span></font></p>
<p><font face="monospace"><span class="blob-code-inner
blob-code-marker js-code-nav-pass " data-code-marker="+"><span
class="pl-en">Looking at the output I am unsure what is
actually being measured by the rxtx_callback example. With a
hardware freq. of 156024300 and about 40 cycles the latency
is about 262ns. But what is this latency? From the time the
packet is received by the NIC to the first time dpdk
interacts with it? Or when I get the packet in my dpdk
program?<br>
</span></span></font></p>
<p><font face="monospace"><span class="blob-code-inner
blob-code-marker js-code-nav-pass " data-code-marker="+"><span
class="pl-en">Thanks</span></span></font></p>
<p><font face="monospace"><span class="blob-code-inner
blob-code-marker js-code-nav-pass " data-code-marker="+"><span
class="pl-en">Arne<br>
</span></span></font></p>
<p><font face="monospace"><span class="blob-code-inner
blob-code-marker js-code-nav-pass " data-code-marker="+"><span
class="pl-en">[0]
<a class="moz-txt-link-freetext" href="https://docs.kernel.org/networking/timestamping.html">https://docs.kernel.org/networking/timestamping.html</a><br>
</span></span><span class="blob-code-inner blob-code-marker
js-code-nav-pass " data-code-marker="+"><span class="pl-s1"></span></span></font></p>
<p><font face="monospace">[1]
<a class="moz-txt-link-freetext" href="https://github.com/DPDK/dpdk/commit/c7e857e16fda217cb9fd3644b66abe19daa3afb3">https://github.com/DPDK/dpdk/commit/c7e857e16fda217cb9fd3644b66abe19daa3afb3</a></font></p>
<p><font face="monospace">[2]
<a class="moz-txt-link-freetext" href="https://github.com/DPDK/dpdk/commit/13ad83f18aaab6e0b5ddf18b3be829254a36eb00#diff-066094c5e52eeca7b5bbcc3f60cea0c8da30bf39bf039bcd809968fe3aeb9dc1L79-R89">https://github.com/DPDK/dpdk/commit/13ad83f18aaab6e0b5ddf18b3be829254a36eb00#diff-066094c5e52eeca7b5bbcc3f60cea0c8da30bf39bf039bcd809968fe3aeb9dc1L79-R89</a><br>
</font></p>
<p><font face="monospace">[1]
<a class="moz-txt-link-freetext" href="https://github.com/DPDK/dpdk/blob/main/examples/rxtx_callbacks/main.c#L101">https://github.com/DPDK/dpdk/blob/main/examples/rxtx_callbacks/main.c#L101</a></font><br>
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