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Document WITNESS_COUNT and WITNESS_NO_VNODE

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Reviewed by: bcr, kib
Differential Revision: D1789
MFC after: 3 days
Sponsored by: EMC / Isilon Storage Division
This commit is contained in:
Enji Cooper 2015-02-06 20:46:46 +00:00
parent 330c544318
commit e15131d39c
1 changed files with 24 additions and 0 deletions
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24
share/man/man4/witness.4
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@ -32,7 +32,9 @@
.Nd lock validation facility
.Sh SYNOPSIS
.Cd options WITNESS
.Cd options WITNESS_COUNT
.Cd options WITNESS_KDB
.Cd options WITNESS_NO_VNODE
.Cd options WITNESS_SKIPSPIN
.Sh DESCRIPTION
The
@ -56,6 +58,28 @@ does not recurse on a non-recursive lock,
or attempt an upgrade on a shared lock held by another thread.
If any of these checks fail, then the kernel will panic.
.Pp
The
.Dv WITNESS_COUNT
kernel option controls the maximum number of
.Xr witness 4
entries that are tracked in the kernel.
The maximum number of entries can be queried via the
.Va debug.witness.count
sysctl.
It can also be set from the
.Xr loader 8
via the
.Va debug.witness.count
environment variable.
.Pp
The
.Dv WITNESS_NO_VNODE
kernel option tells
.Xr witness 4
to ignore locking issues between
.Xr vnode 9
objects.
.Pp
The flag that controls whether or not the kernel debugger is entered when a
lock order violation is detected can be set in a variety of ways.
By default, the flag is off, but if the