NACK/Cmnt: [SRU][B][F][G][PATCH 0/1] dm crypt: add flags to optionally

[Gerald Yang]

Thanks Stefan, I will update the SRU with all related commits

On Tue, May 18, 2021 at 2:42 PM Stefan Bader <stefan.bader at canonical.com>
wrote:

> On 18.05.21 04:56, Gerald Yang wrote:
> > BugLink: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1910976
>
> Above should be https://bugs.launchpad.net/bugs/1910976 but that could be
> done
> when applying. However there seem to be multiple references to this patch
> following its introduction upstream (see below). That does not sound like
> just
> picking this one patch is a good idea.
>
> -Stefan
>
> >
> > === SRU Justification ===
> > [Impact]
> > To get better performance for dm-crypt in some cases, bypass kcryptd
> > workqueue can reduce the overhead in context switch between kworkers,
> > 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
> >
> > Ignat Korchagin (1):
> >    dm crypt: add flags to optionally bypass kcryptd workqueues
> >
> >   drivers/md/dm-crypt.c | 50 ++++++++++++++++++++++++++++++++++++-------
> >   1 file changed, 42 insertions(+), 8 deletions(-)
> >
>
>  > git log --oneline --grep "Fixes: 39d42fa96ba1"
> c87a95dc28b1 dm crypt: defer decryption to a tasklet if interrupts disabled
> 8e14f610159d dm crypt: do not call bio_endio() from the dm-crypt tasklet
> d68b29584c25 dm crypt: use GFP_ATOMIC when allocating crypto requests from
> softirq
> 8abec36d1274 dm crypt: do not wait for backlogged crypto request
> completion in
> softirq
> 4a5caa4af0df dm crypt: document new no_workqueue flags
>
>
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