Before anyone invests in integrating LTTNG with vpp: it’s critical to understand the per-logged-event cost. I may be able to make some time to look at that.
The vppinfra event logger costs O(100 clocks) per logged event. Even at that, we can’t afford to record per-packet events in speed-path data plane nodes. It would be interesting to know when vpp takes a hit due to kernel or other application activity, but not at an exorbitant cost. FWIW... Dave From: vpp-dev@lists.fd.io <vpp-dev@lists.fd.io> On Behalf Of Varun Rapelly Sent: Monday, July 26, 2021 12:08 PM To: v...@barachs.net; vpp-dev@lists.fd.io Subject: Re: [vpp-dev] Event Logs Memory Thanks Dave. Was also exploring LTTNG tracing infra for VPP. Is there any benefit of using LTTNG over elog? Did not find much details about LTTNG in the VPP mail archive either. Is it worth trying? On Mon, Jul 26, 2021 at 4:50 PM <v...@barachs.net <mailto:v...@barachs.net> > wrote: Simply configure “vlib { elog-post-mortem-dump }” and look for the event log in /tmp/elog_post_mortem.<pid>. If vpp crashes in a horrifying way, the post mortem dump may fail. HTH... Dave From: vpp-dev@lists.fd.io <mailto:vpp-dev@lists.fd.io> <vpp-dev@lists.fd.io <mailto:vpp-dev@lists.fd.io> > On Behalf Of Varun Rapelly Sent: Monday, July 26, 2021 4:28 AM To: vpp-dev@lists.fd.io <mailto:vpp-dev@lists.fd.io> Subject: [vpp-dev] Event Logs Memory Hi, Is it possible to retrieve the VPP event logs (elog), if VPP crashes before saving the events logged using the event-logger save command? If the above is not possible, what are the other options to save VPP events/traces in a persistent memory to debug issues in cases like the above? -- Regards, VR -- Regards, Varun Rapelly -- Regards, Varun Rapelly
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