** Description changed:
=== SRU Justification ===
[Impact]
- To get better performance for dm-crypt in some cases, bypass kcryptd
workqueue can reduce the overhead in context switch between workers,
cherry-pick commit 39d42fa96ba1b7d2544db3f8ed5da8fb0d5cb877 from mainline
kernel, and this is not enabled by default
+ To get better performance for dm-crypt in some cases, bypass kcryptd
workqueue can reduce the overhead in context switch between workers,
cherry-pick commit 39d42fa96ba1b7d2544db3f8ed5da8fb0d5cb877 from mainline
kernel, and bypass kcryptd workqueue is not enabled by default
[Fix]
Add flags to bypass kcryptd workqueue
[Test]
create dm-crypt and setup DM_CRYPT_NO_READ_WORKQUEUE and
DM_CRYPT_NO_WRITE_WORKQUEUE, read/write data and run perf record to see if
read/write to the encrypted device will bypass kcryptd workqueue
[Regression Potential]
Low, this feature is disabled by default, need to enable manually
========= original bug description =========
Hi,
I'm asking if it would be possible to cherry-pick patch "dm crypt: add
flags to optionally bypass kcryptd workqueues" into the 5.4 Ubuntu
kernel. This patch has been merged in mainline kernel 5.9
https://github.com/torvalds/linux/commit/39d42fa96ba1b7d2544db3f8ed5da8fb0d5cb877
but was not tagged for the stable tree.
This patch provides important performance gains for some workloads using
dm-crypt / LUKS and cherry-picking it would be very beneficial for dm-
crypt users. You can find details on the expected gain in the following
links:
* https://www.redhat.com/archives/dm-devel/2020-July/msg00138.html
* https://blog.cloudflare.com/speeding-up-linux-disk-encryption/
The patch mostly applies cleanly on the Ubuntu 5.4 kernel, the only
merge conflict is due to the module version at the end of the patch. I
can provide a backport patch if needed.
Thanks,
** Also affects: linux (Ubuntu Groovy)
Importance: Undecided
Status: New
** Also affects: linux (Ubuntu Bionic)
Importance: Undecided
Status: New
** Also affects: linux (Ubuntu Focal)
Importance: Undecided
Status: New
** Changed in: linux (Ubuntu Bionic)
Status: New => In Progress
** Changed in: linux (Ubuntu Focal)
Status: New => In Progress
** Changed in: linux (Ubuntu Groovy)
Status: New => In Progress
** Changed in: linux (Ubuntu Bionic)
Assignee: (unassigned) => gerald.yang (gerald-yang-tw)
** Changed in: linux (Ubuntu Groovy)
Assignee: (unassigned) => gerald.yang (gerald-yang-tw)
** Changed in: linux (Ubuntu Focal)
Assignee: (unassigned) => gerald.yang (gerald-yang-tw)
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https://bugs.launchpad.net/bugs/1910976
Title:
Cherry-pick dm-crypt performance improvement patch from Linux 5.9
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