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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><div style='border:none;border-left:solid blue 1.5pt;padding:0cm 0cm 0cm 4.0pt'><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> taozj888 [mailto:taozj888@163.com] <br><b>Sent:</b> Monday, 13 November 2023 12.47<br><br></span><o:p></o:p></p><div><div><p class=MsoNormal><span style='font-size:10.5pt;font-family:"Arial","sans-serif";color:black'>At 2023-11-13 07:33:49, "Stephen Hemminger" <stephen@networkplumber.org> wrote:<o:p></o:p></span></p></div><pre><span style='color:black'>>On Sun, 12 Nov 2023 07:16:10 +0000<o:p></o:p></span></pre><pre><span style='color:black'>>Trevor Tao <taozj888@163.com> wrote:<o:p></o:p></span></pre><pre><span style='color:black'>><o:p> </o:p></span></pre><pre><span style='color:black'>>> Now the port Rx mq_mode had been set to RTE_ETH_MQ_RX_RSS<o:p></o:p></span></pre><pre><span style='color:black'>>> by default, but some hw and/or virtual interface does not<o:p></o:p></span></pre><pre><span style='color:black'>>> support the RSS and offload mode presupposed, e.g., some<o:p></o:p></span></pre><pre><span style='color:black'>>> virtio interfaces in the cloud don't support<o:p></o:p></span></pre><pre><span style='color:black'>>> RSS and the error msg may like:<o:p></o:p></span></pre><pre><span style='color:black'>>> <o:p></o:p></span></pre><pre><span style='color:black'>>> virtio_dev_configure(): RSS support requested but not supported by<o:p></o:p></span></pre><pre><span style='color:black'>>> the device<o:p></o:p></span></pre><pre><span style='color:black'>>> Port0 dev_configure = -95<o:p></o:p></span></pre><pre><span style='color:black'>>> <o:p></o:p></span></pre><pre><span style='color:black'>>> So to enable the l3fwd running in that environment, the Rx mode requirement<o:p></o:p></span></pre><pre><span style='color:black'>>> can be relaxed to reflect the hardware feature reality here, and the l3fwd<o:p></o:p></span></pre><pre><span style='color:black'>>> can run smoothly then.<o:p></o:p></span></pre><pre><span style='color:black'>>> <o:p></o:p></span></pre><pre><span style='color:black'>>> An option named "relax-rx-mode" is added to enable the relax action<o:p></o:p></span></pre><pre><span style='color:black'>>> here, and it's disabled by default.<o:p></o:p></span></pre><pre><span style='color:black'>>> <o:p></o:p></span></pre><pre><span style='color:black'>>> Signed-off-by: Trevor Tao <taozj888@163.com><o:p></o:p></span></pre><pre><span style='color:black'>><o:p> </o:p></span></pre><pre><span style='color:black'>>Doesn't need to be an option. The application can just look at the offload<o:p></o:p></span></pre><pre><span style='color:black'>>flags and quickly determine that if multiple queues are being used than<o:p></o:p></span></pre><pre><span style='color:black'>>RSS is required. If device doesn't support RSS, then fallback to single<o:p></o:p></span></pre><div><pre><span style='color:black'>>queue with a warning.<o:p></o:p></span></pre></div><div><pre><span style='color:black'><o:p> </o:p></span></pre></div><div><div><pre><span style='font-family:"Arial","sans-serif";color:black'>Hi Stephen:<o:p></o:p></span></pre></div><div><pre><span style='font-family:"Arial","sans-serif";color:black'><o:p> </o:p></span></pre></div><div><pre><span style='font-family:"Arial","sans-serif";color:black'>I think the option here was suggested/required by Konstantin Ananyev <konstantin.v.ananyev@yandex.ru>.<o:p></o:p></span></pre></div><div><pre><span style='font-family:"Arial","sans-serif";color:black'>The discussion thread is listed below:<o:p></o:p></span></pre></div><div><pre><span style='font-family:"Arial","sans-serif";color:black'><o:p> </o:p></span></pre></div><div><pre><span style='font-family:"Arial","sans-serif";color:black'>">>>>Should we probably instead have a new commnad-line option to explicitly <o:p></o:p></span></pre></div><pre style='word-break:break-word !important'><span style='color:black'>>>>>disable RSS?<o:p></o:p></span></pre><pre><span style='color:black'>>>> <o:p></o:p></span></pre><pre><span style='color:black'>>>>>Something like: '--no-rss' or so?<o:p></o:p></span></pre><pre><span style='color:black'>>>> Trevor: the RSS capability for a certain port was got by the rte_eth_dev_info_get() automatically, and we think the user should not care about its status beforehand, but if it's missing, a warning notification for the degrade here would be proposed to make it run smoothly.<o:p></o:p></span></pre><pre><span style='color:black'>>><o:p> </o:p></span></pre><pre><span style='color:black'>>>Personally, I still think it would be better the user will<o:p></o:p></span></pre><pre><span style='color:black'>>>have an ability to disable it explicitly.<o:p></o:p></span></pre><pre><span style='color:black'>>>Same as l3fwd does now with 'parse-ptype'.<o:p></o:p></span></pre><div><pre><span style='color:black'>>><o:p> </o:p></span></pre></div><div><pre><span style='color:black'>"<o:p></o:p></span></pre></div><div><pre><span style='color:#1F497D'><o:p> </o:p></span></pre><pre><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>[Morten]: The “relax-rx-mode” does not explicitly disable RSS, it enables the behavior Stephen suggested: If RSS is not supported by the device, fallback to single queue with a warning. We don’t need an option for this; it should be the default behavior.<o:p></o:p></span></pre><pre><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>[Morten]: I think Konstantin was asking for an option “no-rss” (or “disable-rss”) to force use of single queue (disable RSS), regardless if the device supports RSS or not.<o:p></o:p></span></pre><pre><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></pre></div><div><pre><span style='color:black'>Thanks,<o:p></o:p></span></pre></div><div><pre><span style='color:black'><o:p> </o:p></span></pre></div><div><pre><span style='color:black'>Trevor Tao<o:p></o:p></span></pre></div></div></div></div></div></body></html>