[LU-14442] lctl get_param '-w' option to dump only tunable parameters

Related — Thu, 18 Jan 2024 18:47:32 +0000

For debugging system performance (eg. IO500) it is desirable to have an easy way to collect all of the Lustre tuning parameters for each run. Since "lctl get_param" lists both statistics and tunable parameters, just doing "lctl get_param -R '*'" dumps far too much information to be useful.

Running "lctl list_param -RF '*' | grep '='" will list all of the writable parameters, but unfortunately many of the statistics files are writable so that the statistics can be reset. Most of the statistics parameters have "stats" in the name. The symlinks from lov/target_obds/ and lmv/target_obds/ to the osc and mdc devices are redundant and should be skipped. There are also a few parameters that are write-only that should be skipped, but there is no easy way to tell this externally.

Something equivalent to the following command that lists only read+writable parameters, and exclude some, is close to providing the proper list of tunable parameters:

lctl list_param -RF '*' | grep = | tr -d '=' |
    egrep -v "console|debug_|fail_|force|import|\<nis\>|panic_|peers|sepol|stats|target_obd" |
    sed -e 's/OST[0-9]*/OST*/' -e 's/MDT[0-9]*/MDT*/' -e "s/$(lfs getname  -i)/*/" | sort -u

Having something like "dshbak" or "bash_completion" to collapse common parameters with a '*' would both make the output more compact and easier to read, and make it clear if there are some osc/mdc devices that are tuned differently, whether on purpose or accidentally.

Whamcloud Community JIRA

[LU-14442] lctl get_param '-w' option to dump only tunable parameters