<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<meta name="Generator" content="Microsoft Word 15 (filtered medium)">
<style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
font-size:11.0pt;
font-family:"Calibri",sans-serif;}
span.EmailStyle17
{mso-style-type:personal-compose;
font-family:"Calibri",sans-serif;
color:windowtext;}
.MsoChpDefault
{mso-style-type:export-only;
font-family:"Calibri",sans-serif;}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang="EN-US" link="#0563C1" vlink="#954F72" style="word-wrap:break-word">
<div class="WordSection1">
<p class="MsoNormal">Hi all.<o:p></o:p></p>
<p class="MsoNormal">Newbie question here.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I have been playing with dpdk 21.11 for a week or two and run into something that has me scratching my head a bit.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I’m looking at packet_reorder example. I’m running this sample with 3 cores: 1 RX, 1 Worker, and 1 TX.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">dpdk-packet_ordering -l 0-3 -- -p 3 --disable-reorder<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">In this example:<o:p></o:p></p>
<p class="MsoNormal">RX thread reads the packets from receive queue and puts them in a rx_to_workers ring<o:p></o:p></p>
<p class="MsoNormal">Worker thread reads from the rx_to_workers ring, changes the port number and queues to workers_to_tx ring<o:p></o:p></p>
<p class="MsoNormal">Tx thread reads from workers_to_tx ring and calls rte_eth_tx_buffer<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">What I like to do is access the packet content in the worker thread and print out a few bytes from it.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">What I’m finding is that mbuf_addr value, for the same mbuf, read from RX thread is different than if read in the Worker or TX thread.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">For example, when printing out the address of mbuf, and mbuf_addr values, in the three threads, I get:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">rx_thread<o:p></o:p></p>
<p class="MsoNormal">mbuf = 100e30000<o:p></o:p></p>
<p class="MsoNormal">mbuf_addr = 100e30080<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">worker_thread<o:p></o:p></p>
<p class="MsoNormal">mbuf = 100e30000<o:p></o:p></p>
<p class="MsoNormal">mbuf_addr = 100000000<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">tx_thread<o:p></o:p></p>
<p class="MsoNormal">mbuf = 100e30000<o:p></o:p></p>
<p class="MsoNormal">mbuf_addr = 100000000<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">So although mbuf is the same, the mbuf_addr is different. The packet content is obviously (?) different if read in RX, vs if read in Worker or TX thread.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Is this what is supposed to happen?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Basically: how do I get access to the actual ethernet packet, for reading or modifying, on different lcores; in this case the worker thread.<o:p></o:p></p>
</div>
</body>
</html>