Le 2012-07-03 13:39, Mathieu Desnoyers a écrit : > * Francis Giraldeau ([email protected]) wrote: >> Le 2012-07-03 00:23, Mathieu Desnoyers a écrit : >>> * Francis Giraldeau ([email protected]) wrote: >>>> By writing to the file /proc/lttng_uevent, a user-space application >>>> creates a >>>> kernel event. The event's payload is by default UTF-8 text, but any data >>>> can be >>>> written, up to 1024 bytes. Null-character is optional and is not enforced. >>> >>> The 1024 byte limit is removed now, right ? >> >> Exactly. > > OK, please provide an updated version with the updated changelog.
Fixed. > >> >>>> + * Expose kernel tracer to user-space through /proc/lttng >> >> I just saw a typo here, we should read "through /proc/lttng_uevent" > > Same here. Fixed. > >> >>>> + * Copyright (C) 2009-2012 Mathieu Desnoyers >>>> <[email protected]> >>> >>> you might want to add your own copyright in here too. >> >> I transfer you the copyright. > > Thanks! > > One more thing: > > In the testing you did, did you try running, in parallel: > > for a in $(seq 1 10000); do > modprobe nameofuevent_module > rmmod nameofevent_module > done > > and in 4 another terminals: > > echo "blahblahblah" > /proc/lttng_uevent > > ? > > I understand that you tested only the write path in parallel, but I'm > not sure, from your changelog, that you stress-tested load/unload vs > write. The test I did was to write in parallel to /proc/lttng_uevent and see the behavior. It takes about 15us on my i5 2.5Ghz to log an event this way in a tight loop, so yeah, it's quite slow. It's not possible to remove the module while an active tracing session references the event lttng_uevent. I tested insertion/removal of the module while tracing with the previous version that was using RCU and it was working well. Cheers, Francis
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