New undocumented feature, added in e83068a5f:
dm mpath: add optional "queue_mode" feature
Allow a user to specify an optional feature 'queue_mode <mode>' where
<mode> may be "bio", "rq" or "mq" -- which corresponds to bio-based,
request_fn rq-based, and blk-mq rq-based respectively.
If the queue_mode feature isn't specified the default for the
"multipath" target is still "rq" but if dm_mod.use_blk_mq is set to Y
it'll default to mode "mq".
This new queue_mode feature introduces the ability for each multipath
device to have its own queue_mode (whereas before this feature all
multipath devices effectively had to have the same queue_mode).
Also add more info to other features.
Cc: Mike Snitzer <snitzer@xxxxxxxxxx>
Cc: Christophe Varoqui <christophe.varoqui@xxxxxxxxxxx>
Cc: device-mapper development <dm-devel@xxxxxxxxxx>
Signed-off-by: Xose Vazquez Perez <xose.vazquez@xxxxxxxxx>
---
multipath/multipath.conf.5 | 36 ++++++++++++++++++++++++------------
1 file changed, 24 insertions(+), 12 deletions(-)
diff --git a/multipath/multipath.conf.5 b/multipath/multipath.conf.5
index fd4b1f2..40df315 100644
--- a/multipath/multipath.conf.5
+++ b/multipath/multipath.conf.5
@@ -3,11 +3,11 @@
.\" Make sure there are no errors with:
.\" groff -z -wall -b -e -t multipath/multipath.conf.5
.\"
-.\" TODO: Look for XXX
+.\" TODO: Look for XXX and ???
.\"
.\" ----------------------------------------------------------------------------
.
-.TH MULTIPATH.CONF 5 2016-08-09 "Linux"
+.TH MULTIPATH.CONF 5 2016-08-12 "Linux"
.
.
.\" ----------------------------------------------------------------------------
@@ -166,12 +166,15 @@ Loop through every path in the path group, sending the same amount of IO to
each. Some aspects of behavior can be controlled with the attributes:
\fIrr_min_io\fR, \fIrr_min_io_rq\fR and \fIrr_weight\fR.
.TP
+.\" XXX
.I "queue-length 0"
-Send the next bunch of IO down the path with the least amount of outstanding IO.
+(Since ??? kernel) Choose the path for the next bunch of IO based on the amount
+of outstanding IO to the path.
.TP
+.\" XXX
.I "service-time 0"
-Choose the path for the next bunch of IO based on the amount of outstanding IO
-to the path and its relative throughput.
+(Since ??? kernel) Choose the path for the next bunch of IO based on the amount
+of outstanding IO to the path and its relative throughput.
.TP
Default value is: \fBservice-time 0\fR
.RE
@@ -333,22 +336,31 @@ Default value is: \fB<unset>\fR
.TP
.B features
Specify any device-mapper features to be used. Syntax is \fInum list\fR
-where \fInum\fR is the number, between 0 and 6, of features in \fIlist\fR.
+where \fInum\fR is the number, between 0 and 8, of features in \fIlist\fR.
Possible values for the feature list are:
.RS
.TP 12
+.\" XXX
.I queue_if_no_path
-(Superseded by \fIno_path_retry\fR) Queue IO if no path is active. Identical to
-the \fIno_path_retry\fR with \fIqueue\fR value. See KNOWN ISSUES.
+(Superseded by \fIno_path_retry\fR) (Since ??? kernel) Queue IO if no path is active.
+Identical to the \fIno_path_retry\fR with \fIqueue\fR value. See KNOWN ISSUES.
.TP
.I no_partitions
Disable automatic partitions generation via kpartx.
.TP
-.I pg_init_retries
-Number of times to retry pg_init, it must be between 1 and 50.
+.\" XXX
+.I pg_init_retries <times>
+(Since ??? kernel) Number of times to retry pg_init, it must be between 1 and 50.
.TP
-.I pg_init_delay_msecs
-Number of msecs before pg_init retry, it must be between 0 and 60000.
+.\" XXX
+.I pg_init_delay_msecs <msecs>
+(Since ??? kernel) Number of msecs before pg_init retry, it must be between 0 and 60000.
+.TP
+.\" XXX
+.I queue_mode <mode>
+(Since ??? kernel) Select the the queue_mode per multipath device.
+Where <mode> can be \fIbio\fR, \fIrq\fR or \fImq\fR. Which corresponds to
+bio-based, request_fn rq-based, and blk-mq rq-based respectively.
.TP
Default value is: \fB0\fR
.RE
--
2.7.4
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