path: root/Documentation
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authorLinus Torvalds <torvalds@linux-foundation.org>2015-02-21 13:28:45 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2015-02-21 13:28:45 -0800
commita911dcdba190ddf77e9199b9917156f879f42d4b (patch)
treec94d84a9fa48520cd993670a0b4f434c4dcb48db /Documentation
parente20d3ef5406d3a28b76a63905b2a6bd3fb95c377 (diff)
parent22aa66a3ee5b61e0f4a0bfeabcaa567861109ec3 (diff)
Merge tag 'dm-3.20-changes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm
Pull more device mapper changes from Mike Snitzer: - Significant dm-crypt CPU scalability performance improvements thanks to changes that enable effective use of an unbound workqueue across all available CPUs. A large battery of tests were performed to validate these changes, summary of results is available here: https://www.redhat.com/archives/dm-devel/2015-February/msg00106.html - A few additional stable fixes (to DM core, dm-snapshot and dm-mirror) and a small fix to the dm-space-map-disk. * tag 'dm-3.20-changes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: dm snapshot: fix a possible invalid memory access on unload dm: fix a race condition in dm_get_md dm crypt: sort writes dm crypt: add 'submit_from_crypt_cpus' option dm crypt: offload writes to thread dm crypt: remove unused io_pool and _crypt_io_pool dm crypt: avoid deadlock in mempools dm crypt: don't allocate pages for a partial request dm crypt: use unbound workqueue for request processing dm io: reject unsupported DISCARD requests with EOPNOTSUPP dm mirror: do not degrade the mirror on discard error dm space map disk: fix sm_disk_count_is_more_than_one()
Diffstat (limited to 'Documentation')
1 files changed, 14 insertions, 1 deletions
diff --git a/Documentation/device-mapper/dm-crypt.txt b/Documentation/device-mapper/dm-crypt.txt
index c81839b52c4d..ad697781f9ac 100644
--- a/Documentation/device-mapper/dm-crypt.txt
+++ b/Documentation/device-mapper/dm-crypt.txt
@@ -51,7 +51,7 @@ Parameters: <cipher> <key> <iv_offset> <device path> \
Otherwise #opt_params is the number of following arguments.
Example of optional parameters section:
- 1 allow_discards
+ 3 allow_discards same_cpu_crypt submit_from_crypt_cpus
Block discard requests (a.k.a. TRIM) are passed through the crypt device.
@@ -63,6 +63,19 @@ allow_discards
used space etc.) if the discarded blocks can be located easily on the
device later.
+ Perform encryption using the same cpu that IO was submitted on.
+ The default is to use an unbound workqueue so that encryption work
+ is automatically balanced between available CPUs.
+ Disable offloading writes to a separate thread after encryption.
+ There are some situations where offloading write bios from the
+ encryption threads to a single thread degrades performance
+ significantly. The default is to offload write bios to the same
+ thread because it benefits CFQ to have writes submitted using the
+ same context.
Example scripts
LUKS (Linux Unified Key Setup) is now the preferred way to set up disk

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