How does the 'lttng snapshot record' command affect a running (active) trace? I presume very little, only to the extent that the consumer daemon servicing the request "steals" CPU cycles from the session daemon busily shoving records into the buffer.
Say we have a trace running in flight recorder mode and a heavy flow of events into its buffers. When the 'lttng snapshot record' command is issued, a consumer starts at the earliest (oldest) sub-buffer and starts dumping the records to a trace directory. As its "cursor" advances around the ring of buffers, tracing continues. By the time it wraps around the ring, the tracer may very well have re-used a number of sub-buffers, so the consumer keeps going, trying to catch up. Am I right in supposing that if the reading and writing speeds are well matched, this could theoretically go on nearly forever, generating a huge trace? (That's what the snapshot --max-size option is for, along with the enable-channel --tracefile-size and --tracefile-count options) Daniel U. Thibault Protection des systèmes et contremesures (PSC) | Systems Protection & Countermeasures (SPC) Cyber sécurité pour les missions essentielles (CME) | Mission Critical Cyber Security (MCCS) R & D pour la défense Canada - Valcartier (RDDC Valcartier) | Defence R&D Canada - Valcartier (DRDC Valcartier) 2459 route de la Bravoure Québec QC G3J 1X5 CANADA Vox : (418) 844-4000 x4245 Fax : (418) 844-4538 NAC : 918V QSDJ <http://www.travelgis.com/map.asp?addr=918V%20QSDJ> Gouvernement du Canada | Government of Canada <http://www.valcartier.drdc-rddc.gc.ca/> _______________________________________________ lttng-dev mailing list [email protected] http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
