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[PR 195033] Document mps.enable_ssu

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mps(4) sends StartStopUnit to SATA direct-access devices during shutdown.
Document the tunables which control that behavior.

PR:		195033
Reviewed by:	scottl
Approved by:	jhb
MFC after:	2 weeks
Differential Revision:	https://reviews.freebsd.org/D4456
This commit is contained in:
rpokala 2015-12-11 21:50:59 +00:00
parent 662efc558a
commit 7fd0d14bf5
1 changed files with 37 additions and 2 deletions
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39
share/man/man4/mps.4
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@ -34,7 +34,7 @@
.\" $Id: //depot/SpectraBSD/head/share/man/man4/mps.4#6 $ .\" $Id: //depot/SpectraBSD/head/share/man/man4/mps.4#6 $
.\" $FreeBSD$ .\" $FreeBSD$
.\" .\"
.Dd January 3, 2013 .Dd December 9, 2015
.Dt MPS 4 .Dt MPS 4
.Os .Os
.Sh NAME .Sh NAME
@ -129,6 +129,8 @@ driver instance, set the following tunable value in
dev.mps.X.disable_msix=1 dev.mps.X.disable_msix=1
.Ed .Ed
.Pp .Pp
where X is the adapter number.
.Pp
To set the maximum number of DMA chains allocated for all adapters, To set the maximum number of DMA chains allocated for all adapters,
set the following variable in set the following variable in
.Xr loader.conf 5 : .Xr loader.conf 5 :
@ -166,6 +168,39 @@ The maximum number of active I/O command seen since boot is shown in the
dev.mps.X.io_cmds_highwater dev.mps.X.io_cmds_highwater
.Xr sysctl 8 .Xr sysctl 8
variable. variable.
.Pp
The adapter can issue the
.Sy StartStopUnit
SCSI command to SATA direct-access devices during shutdown, to allow the
device to quiesce before being powered down.
To control this feature for all adapters, set the
.Bd -literal -offset indent
hw.mps.enable_ssu
.Ed
.Pp
tunable value in
.Xr loader.conf 5
to one of the following values:
.Bl -tag -width 6n -offset indent
.It 0
Do not send SSU to either HDDs or SSDs.
.It 1
Send SSU to SSDs, but not to HDDs; this is the default value.
.It 2
Send SSU to HDDs, but not to SSDs.
.It 3
Send SSU to both HDDs and SSDs.
.El
.Pp
To control the feature for a specific adapter, set the following tunable
value in
.Xr loader.conf 5 :
.Bd -literal -offset indent
dev.mps.X.enable_ssu
.Ed
.Pp
where X is the adapter number.
The same set of values are valid as for all adapters.
.Sh DEBUGGING .Sh DEBUGGING
To enable debugging prints from the To enable debugging prints from the
.Nm .Nm
@ -218,7 +253,7 @@ This man page was written by
This driver has a couple of known shortcomings: This driver has a couple of known shortcomings:
.Bl -bullet -compact .Bl -bullet -compact
.It .It
No userland utility available (e.g. No userland utility available (e.g.,
.Xr mptutil 8 ) . .Xr mptutil 8 ) .
.It .It
The driver probes devices sequentially. The driver probes devices sequentially.