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<p class="MsoNormal"><span style="font-size:12.0pt">Hi all,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:12.0pt">My idea is to pre-allocate memory on system startup which can later be used by lttng for tracing. It should work like flight recorder mode without extracting data from ringbuffers to trace file
while recording data. Data extraction of shm ringbuffers should be done when recording has been finished.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:12.0pt">As per documention with option
</span><span lang="EN-US" style="font-size:12.0pt;font-family:"Courier New"">`--shm-path‘</span><span lang="EN-US" style="font-size:12.0pt"> ringbuffer for tracing can be created in shared memory. With
</span><span lang="EN-US" style="font-size:12.0pt;font-family:"Courier New"">lttng-crash</span><span lang="EN-US" style="font-size:12.0pt"> data can be extracted from ringbuffer.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:12.0pt">Can this option be used with shared memory in volatile memory (default ram), too? And is it possible to record kernel space traces with this option?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:12.0pt">I tried <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:12.0pt;font-family:"Courier New"">lttng create testshm --shm-path=/dev/shm --snapshot<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:12.0pt;font-family:"Courier New"">lttng enable-channel c0 -s testshm -k<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:12.0pt;font-family:"Courier New"">lttng enable-event -s testshm -c c0 -k -a<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:12.0pt;font-family:"Courier New"">lttng start<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:12.0pt;font-family:"Courier New"">lttng stop<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:12.0pt;font-family:"Courier New"">lttng-crash -extract=/home/test /dev/shm<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:12.0pt">With lttng and lttng-crash everything seems to work fine (no error messages).<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:12.0pt">However the extract folder keeps empty.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:12.0pt">Has someone researched into this option and can help to clarify the points?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:DE"><o:p> </o:p></span></p>
<p class="MsoNormal">Thanks,<o:p></o:p></p>
<p class="MsoNormal">Thomas<o:p></o:p></p>
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