[LU-14590] add "dshbak" output aggregation equivalent for "lctl get_param"

• Type: Improvement
• Resolution: Unresolved
• Priority: Minor
• Assignee: WC Triage
• Reporter: Andreas Dilger

Description

When running "lctl get_param" on a system with hundreds of OSTs and MDTs, and thousands of clients, often there are are many lines of output that are identical for all devices. For example:

# lctl get_param ldlm.namespaces.*.*
ldlm.namespaces.testfs-OST0000-osc-MDT0000.contended_locks=32
ldlm.namespaces.testfs-OST0000-osc-MDT0000.contention_seconds=2
ldlm.namespaces.testfs-OST0000-osc-MDT0000.ctime_age_limit=10
ldlm.namespaces.testfs-OST0000-osc-MDT0000.dirty_age_limit=10
ldlm.namespaces.testfs-OST0000-osc-MDT0000.early_lock_cancel=0
ldlm.namespaces.testfs-OST0000-osc-MDT0000.lock_count=0
ldlm.namespaces.testfs-OST0000-osc-MDT0000.lock_timeouts=0
ldlm.namespaces.testfs-OST0000-osc-MDT0000.lock_unused_count=0
ldlm.namespaces.testfs-OST0000-osc-MDT0000.lru_max_age=3900000
ldlm.namespaces.testfs-OST0000-osc-MDT0000.lru_size=0
ldlm.namespaces.testfs-OST0000-osc-MDT0000.max_nolock_bytes=0
ldlm.namespaces.testfs-OST0000-osc-MDT0000.max_parallel_ast=1024
ldlm.namespaces.testfs-OST0000-osc-MDT0001.contended_locks=32
ldlm.namespaces.testfs-OST0000-osc-MDT0001.contention_seconds=2

:
:
ldlm.namespaces.testfs-OST0102-osc-MDT0013.contended_locks=32
ldlm.namespaces.testfs-OST0102-osc-MDT0013.contention_seconds=2
ldlm.namespaces.testfs-OST0102-osc-MDT0013.ctime_age_limit=10
ldlm.namespaces.testfs-OST0102-osc-MDT0013.dirty_age_limit=10
ldlm.namespaces.testfs-OST0102-osc-MDT0013.early_lock_cancel=0
ldlm.namespaces.testfs-OST0102-osc-MDT0013.lock_count=0
ldlm.namespaces.testfs-OST0102-osc-MDT0013.lock_timeouts=0
ldlm.namespaces.testfs-OST0102-osc-MDT0013.lock_unused_count=0
ldlm.namespaces.testfs-OST0102-osc-MDT0013.lru_max_age=3900000
ldlm.namespaces.testfs-OST0102-osc-MDT0013.lru_size=0
ldlm.namespaces.testfs-OST0102-osc-MDT0013.max_nolock_bytes=0
ldlm.namespaces.testfs-OST0102-osc-MDT0013.max_parallel_ast=1024

but it would be much more convenient if the output was aggregated with wildcards in a manner similar to how multiple parameters are specified with "lctl set_param":

ldlm.namespaces.*.contended_locks=32
ldlm.namespaces.*.contention_seconds=2
ldlm.namespaces.*.ctime_age_limit=10
ldlm.namespaces.*.dirty_age_limit=10
ldlm.namespaces.*.early_lock_cancel=0
ldlm.namespaces.*.lock_count=0
ldlm.namespaces.*.lock_timeouts=0
ldlm.namespaces.*.lock_unused_count=0
ldlm.namespaces.testfs-OST00[00-14]-osc-MDT00[00-13].lru_max_age=3900000
ldlm.namespaces.testfs-OST00[15-63]-osc-MDT00[00-11,13].lru_max_age=3900000
ldlm.namespaces.testfs-OST00[15-63]-osc-MDT0012.lru_max_age=100000
ldlm.namespaces.*.lru_size=0
ldlm.namespaces.*.max_nolock_bytes=0
ldlm.namespaces.*.max_parallel_ast=1024

or something similar (it would be implementation dependent how disjoint regions of identifiers would be shown). This would not only allow reducing the amount of output, but also make it much more obvious in cases where there are differences in the settings (e.g. lru_max_age above).

Something like "lctl merge_param" would take the output of "lctl get_param" as input and merge the lines, either by optionally (with new '-m' option) forking a process to pipe the output of "lctl get_param -m" into, or allowing the output of previously-captured "get_param" output to be aggregated (possibly from dsh or clush running on multiple nodes at once).

There would have to be some implementation-specific smarts in the aggregation, for example to understand that client instance identifiers can be aggregated.

Issue Links

• is related to: LU-14442 lctl get_param '-w' option to dump only tunable/writeable parameters