Re: [PATCH dlm/next 8/8] md-cluster: use DLM_LSFL_SOFTIRQ for dlm_new_lockspace()

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On Thu, Jun 6, 2024 at 7:34 AM Alexander Aring <aahringo@xxxxxxxxxx> wrote:
>
> Hi Heming,
>
> On Wed, Jun 5, 2024 at 10:48 PM Heming Zhao <heming.zhao@xxxxxxxx> wrote:
> >
> > On 6/6/24 02:54, Alexander Aring wrote:
> > > Hi,
> > >
> > > On Mon, Jun 3, 2024 at 5:56 PM Alexander Aring <aahringo@xxxxxxxxxx> wrote:
> > >>
> > >> Recently the DLM subsystem introduced the flag DLM_LSFL_SOFTIRQ for
> > >> dlm_new_lockspace() to signal the capability to handle DLM ast/bast
> > >> callbacks in softirq context to avoid an additional context switch due
> > >> the DLM callback workqueue.
> > >>
> > >> The md-cluster implementation only does synchronized calls above the
> > >> async DLM API. That synchronized API should may be also offered by DLM,
> > >> however it is very simple as md-cluster callbacks only does a complete()
> > >> call for their wait_for_completion() wait that is occurred after the
> > >> async DLM API call. This patch activates the recently introduced
> > >> DLM_LSFL_SOFTIRQ flag that allows that the DLM callbacks are executed in
> > >> a softirq context that md-cluster can handle. It is reducing a
> > >> unnecessary context workqueue switch and should speed up DLM in some
> > >> circumstance.
> > >>
> > >
> > > Can somebody with a md-cluster environment test it as well? All I was
> > > doing was (with a working dlm_controld cluster env):
> > >
> > > mdadm --create /dev/md0 --bitmap=clustered --metadata=1.2
> > > --raid-devices=2 --level=mirror /dev/sda /dev/sdb
> > >
> > > sda and sdb are shared block devices on each node.
> > >
> > > Create a /etc/mdadm.conf with the content mostly out of:
> > >
> > > mdadm --detail --scan
> > >
> > > on each node.
> > >
> > > Then call mdadm --assemble on all nodes where not "mdadm --create ..." happened.
> > > I hope that is the right thing to do and I had with "dlm_tool ls" a
> > > UUID as a lockspace name with some md-cluster locks being around.
> >
> > The above setup method is correct.
> > SUSE doc [1] provides more details on assembling the clustered array.
> >
>
> yea, I saw that and mostly cut it down into the necessary steps in my
> development setup.
>
> Thanks for confirming I did something right here.
>
> > [1]: https://documentation.suse.com/fr-fr/sle-ha/15-SP5/html/SLE-HA-all/cha-ha-cluster-md.html#sec-ha-cluster-md-create
> >
> > >
> > > To bring this new flag upstream, would it be okay to get this through
> > > dlm-tree? I am requesting here for an "Acked-by" tag from the md
> > > maintainers.
> > >
> >
> > I compiled & tested the dlm-tree [2] with SUSE CI env, and didn't see these
> > patches introduce new issue.
> >
>
> Thanks for doing that. So that means you tried the dlm-tree with this
> patch series applied?
>
> Song or Yu, can I get an "Acked-by" from you and an answer if it is
> okay that this md-cluster.c patch goes upstream via dlm-tree?

LGTM.

Acked-by: Song Liu <song@xxxxxxxxxx>

Yes, let's route this via dlm-tree.

Thanks,
Song





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