<div dir="ltr">Hi,<div><br></div><div>Taking a number of snapshots always showed the events in the buffer, before the</div><div>commit de3fb857f034c208c135a10a3cdec2dfe43fbda6 </div><div><div><br></div><div><div> Fix: ust-consumer: flush empty packets on snapshot channel</div><div> </div><div> Snapshot operation on a non-stopped stream should use a "final" flush to</div><div> ensure empty packets are flushed, so we gather timestamps at the moment</div><div> where the snapshot is taken. This is important for streams that have a</div><div> low amount of activity, which might be on an empty packet when the</div><div> snapshot is triggered.</div><div><br></div><div>After this the number of snapshots that can be taken and getting events is equal to number of sub-buffers!?</div><div>I think this i BUG!</div><div><br></div><div>The following test script shows the problem!</div><div>-----------------------------------------------------------------</div><div><div>#!/bin/sh</div><div><br></div><div>TRACEAPP="/usr/lib/lttng-tools/ptest/tests/utils/testapp/gen-ust-events/gen-ust-events 1"</div><div>TRACEPATH=$HOME/lttng-snapshots<br></div><div>SESSION=tracetest</div><div>CHANNEL=tracechannel</div><div><br></div><div># cleanup</div><div>lttng destroy $SESSION<br></div><div>rm -rf $TRACEPATH</div><div>sleep 1</div><div><br></div><div>lttng create $SESSION --snapshot -U file://$TRACEPATH</div><div>lttng enable-channel $CHANNEL -u --subbuf-size 4k --num-subbuf 2</div><div>lttng enable-event -a -u -c $CHANNEL -s $SESSION</div><div>lttng start $SESSION</div><div>lttng --version</div><div>#lttng list $SESSION</div><div><br></div><div>$TRACEAPP <br></div><div>sleep 1</div><div><br></div><div>for i in $(seq 1 5); do</div><div> lttng snapshot record --session $SESSION --name $i-something</div><div> sleep 1</div><div> echo "------------------------------------"</div><div> echo " $i print events" </div><div> babeltrace $TRACEPATH/$i-something* | head -1</div><div>done</div></div><div>------------------------------------------------------------------------</div><div><br></div><div>BEFOR the patch the output is like this (I have removed some lines to make it easier to read);</div><div>--------------------------------------------------------------------------------------------------------------------------</div><div><div>Session tracetest created.<br></div><div>Default snapshot output set to: file:///root/lttng-snapshots</div><div>Snapshot mode set. Every channel enabled for that session will be set in overwrite mode and mmap output.</div><div>UST channel tracechannel enabled for session tracetest</div><div>All UST events are enabled in channel tracechannel</div><div>Tracing started for session tracetest</div><div>lttng (LTTng Trace Control) 2.7.2</div><div><br></div><div>--- create some user events ---<br></div><div>Snapshot recorded successfully for session tracetest</div><div>------------------------------------</div><div> 1 print events</div><div>[15:02:11.886716015] (+?.?????????) axxiaarm lttng_ust_statedump:start: { cpu_id = 9 }, { }</div><div>------------------------------------<br></div><div>Snapshot recorded successfully for session tracetest</div><div> 2 print events</div><div><div>[15:02:11.886716015] (+?.?????????) axxiaarm lttng_ust_statedump:start: { cpu_id = 9 }, { }</div></div></div><div><div><div>------------------------------------<br></div><div>Snapshot recorded successfully for session tracetest</div><div> 3 print events</div><div>[15:02:11.886716015] (+?.?????????) axxiaarm lttng_ust_statedump:start: { cpu_id = 9 }, { }</div></div></div><div><div><div>------------------------------------<br></div><div>Snapshot recorded successfully for session tracetest</div><div> 4 print events</div><div>[15:02:11.886716015] (+?.?????????) axxiaarm lttng_ust_statedump:start: { cpu_id = 9 }, { }</div></div></div><div><div><div>------------------------------------<br></div><div>Snapshot recorded successfully for session tracetest</div><div> 5 print events</div><div>[15:02:11.886716015] (+?.?????????) axxiaarm lttng_ust_statedump:start: { cpu_id = 9 }, { }</div></div></div><div><br></div><div><div><br></div><div>AFTER the patch the output is like this (I have removed some lines to make it easier to read);</div><div>--------------------------------------------------------------------------------------------------------------------------</div><div><div>Session tracetest created.<br></div><div>Default snapshot output set to: file:///root/lttng-snapshots</div><div>Snapshot mode set. Every channel enabled for that session will be set in overwrite mode and mmap output.</div><div>UST channel tracechannel enabled for session tracetest</div><div>All UST events are enabled in channel tracechannel</div><div>Tracing started for session tracetest</div><div>lttng (LTTng Trace Control) 2.7.5</div><div><br></div><div>--- create some user events ---<br></div><div>Snapshot recorded successfully for session tracetest</div><div>------------------------------------</div><div> 1 print events</div><div>[15:02:11.886716015] (+?.?????????) axxiaarm lttng_ust_statedump:start: { cpu_id = 9 }, { }</div><div>------------------------------------<br></div><div>Snapshot recorded successfully for session tracetest</div><div> 2 print events</div><div>[15:02:11.886716015] (+?.?????????) axxiaarm lttng_ust_statedump:start: { cpu_id = 9 }, { }</div></div><div><div>------------------------------------<br></div><div>Snapshot recorded successfully for session tracetest</div><div> 3 print events</div><div>------------------------------------<br></div></div><div><div>Snapshot recorded successfully for session tracetest</div><div> 4 print events</div><div>------------------------------------<br></div></div><div><div>Snapshot recorded successfully for session tracetest</div><div> 5 print events</div><div><br></div></div></div></div><div><br></div><div>Tested on 2.7.5 and 2.8.2 with the same result<br clear="all"><div><div class="gmail_signature"><br></div><div class="gmail_signature">Regards</div><div class="gmail_signature">Anders Wallin</div></div>
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