Viewing: ldlm.namespaces.contention_seconds.4
.TH LDLM.NAMESPACES.CONTENTION_SECONDS 4 2026-04-29 Lustre "Lustre Kernel Interfaces"
.SH NAME
ldlm.namespaces.contention_seconds \- LDLM lock contention detection window
.SH SYNOPSIS
.SY "lctl get_param"
.BI ldlm.namespaces.filter- FSNAME-* .contention_seconds
.SY "lctl set_param"
.BI ldlm.namespaces.filter- FSNAME-* .contention_seconds= SECONDS
.YS
.SS PROPERTIES
.TP
.B Perms
.BR 644 " | " -rw-r--r--
.br
Writing a value outside the supported range fails with EINVAL
.TP
.B Scope
Per OST filter (OSS) namespace only
.TP
.B Config
present on OSS nodes
.TP
.B Default
.RB ldlm.namespaces.filter-*.contention_seconds= 4
.TP
.B Valid Range
.RB ldlm.namespaces.filter-*.contention_seconds= 1
.RB ldlm.namespaces.filter-*.contention_seconds= 16
.SH DESCRIPTION
.B ldlm.namespaces.filter-*.contention_seconds
sets the rolling time window used by the LDLM extent lock contention detector.
.PP
The detector tracks conflicting lock activity for each resource over this
window. When the amount of conflicting activity is more than the
.B ldlm.namespaces.filter-*.contended_locks
threshold, the resource is treated as contended. Conflicting lock requests
during that contended state increment
.BR ldlm.namespaces.contention_events (4).
.PP
Values from 1 to 16 seconds are accepted.
.B Power-of-two
windows (4, 8 or 16 seconds) are
.B recommended
for performance, because they use an optimized rolling-counter calculation path.
Other values are accepted and stored exactly as written.
.PP
Larger windows accumulate background activity and may dilute bursts; pair a
larger
.B ldlm.namespaces.filter-*.contention_seconds
with proportionally larger
.B ldlm.namespaces.filter-*.contended_locks
to keep the effective event-rate threshold meaningful.
.PP
Writing a value outside the supported range fails with
.BR EINVAL .
.PP
Run the command on the node that owns the namespace to be inspected or
changed. Only namespaces that exist on the local node are shown.
.SH MODULES
This parameter applies to OST filter namespaces:
.EX
.BI ldlm.namespaces.filter- FSNAME-* .contention_seconds
.EE
.SH EXAMPLES
Show the contention detection window for OST filter namespaces:
.EX
.RB "oss# " lctl " get_param " ldlm.namespaces.filter-*.contention_seconds
ldlm.namespaces.filter-lustre-OST0000_UUID.contention_seconds=4
.EE
.PP
Set the contention detection window for OST filter namespaces to 8 seconds:
.EX
.RB "oss# " lctl " set_param " ldlm.namespaces.filter-*.contention_seconds=8
ldlm.namespaces.filter-lustre-OST0000_UUID.contention_seconds=8
.EE
.SH AVAILABILITY
.B ldlm.namespaces.filter-*.contention_seconds
is part of the
.BR lustre (7)
filesystem package since release 2.18.0.
.\" commit #
.SH SEE ALSO
.BR ldlm.namespaces.contention_events (4),
.BR ldlm.namespaces.contention_hold_seconds (4),
.BR lustre (7),
.BR lctl-get_param (8),
.BR lctl-set_param (8)
