summaryrefslogtreecommitdiff
path: root/Documentation/device-mapper
diff options
context:
space:
mode:
authorMikulas Patocka <mpatocka@redhat.com>2018-04-17 01:33:14 +0300
committerMike Snitzer <snitzer@redhat.com>2018-07-27 22:24:19 +0300
commitcda6b5ab7f5935565ed5b9bbc385bd1d0a3feb75 (patch)
treef9874d8e3e6d0f6dbefcba98c6835f37694f6009 /Documentation/device-mapper
parent3876ac76f02ac2a7b3d96f813c0ee1070e7a8c8e (diff)
downloadlinux-cda6b5ab7f5935565ed5b9bbc385bd1d0a3feb75.tar.xz
dm delay: add flush as a third class of IO
Add a new class for dm-delay that delays flush requests. Previously, flushes were delayed as writes, but it caused problems if the user needed to create a device with one or a few slow sectors for the purpose of testing - all flushes would be forwarded to this device and delayed, and that skews the test results. Fix this by allowing to select 0 delay for flushes. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'Documentation/device-mapper')
-rw-r--r--Documentation/device-mapper/delay.txt3
1 files changed, 2 insertions, 1 deletions
diff --git a/Documentation/device-mapper/delay.txt b/Documentation/device-mapper/delay.txt
index 4b1d22a44ce4..6426c45273cb 100644
--- a/Documentation/device-mapper/delay.txt
+++ b/Documentation/device-mapper/delay.txt
@@ -5,7 +5,8 @@ Device-Mapper's "delay" target delays reads and/or writes
and maps them to different devices.
Parameters:
- <device> <offset> <delay> [<write_device> <write_offset> <write_delay>]
+ <device> <offset> <delay> [<write_device> <write_offset> <write_delay>
+ [<flush_device> <flush_offset> <flush_delay>]]
With separate write parameters, the first set is only used for reads.
Offsets are specified in sectors.