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Feature #570
closedlttng-tools 2.2.0-rc2: enable-channel man pages ought to mention minimum sub-buffer sizes
Start date:
06/25/2013
Due date:
% Done:
0%
Estimated time:
Description
It seems the minimum size of the LTTng sub-buffers is 4096 bytes (for either domain and either buffering scheme):
$ sudo -H lttng create s Session s created. Traces will be written in /root/lttng-traces/s-20130625-101152 $ sudo -H lttng enable-channel k1 -k --subbuf-size 131072 Kernel channel k1 enabled for session s $ sudo -H lttng enable-channel k2 -k --subbuf-size 65536 Kernel channel k2 enabled for session s $ sudo -H lttng enable-channel k3 -k --subbuf-size 32768 Kernel channel k3 enabled for session s $ sudo -H lttng enable-channel k4 -k --subbuf-size 16384 Kernel channel k4 enabled for session s $ sudo -H lttng enable-channel k5 -k --subbuf-size 8192 Kernel channel k5 enabled for session s $ sudo -H lttng enable-channel k6 -k --subbuf-size 4096 Kernel channel k6 enabled for session s $ sudo -H lttng enable-channel k7 -k --subbuf-size 2048 PERROR [20531/20631]: ioctl kernel create channel: Invalid argument (in kernel_create_channel() at kernel.c:144) Error: Channel k7: Kernel create channel failed (session s) Warning: Some command(s) went wrong
$ sudo -H lttng create ss Session ss created. Traces will be written in /root/lttng-traces/ss-20130625-101446 $ sudo -H lttng enable-channel k7 -k --subbuf-size 2048 PERROR [20531/20631]: ioctl kernel create channel: Invalid argument (in kernel_create_channel() at kernel.c:144) Error: Channel k7: Kernel create channel failed (session ss) Warning: Some command(s) went wrong $ sudo -H lttng enable-channel u7 -u --subbuf-size 2048 Error: Channel u7: Invalid parameter (session ss) Warning: Some command(s) went wrong $ sudo -H lttng enable-channel u6 -u --subbuf-size 4096 UST channel u6 enabled for session ss
This should be mentioned in the man pages.
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