[Linux-cluster] [RFC] Generic Kernel API
daniel at osdl.org
Wed Sep 29 23:55:41 UTC 2004
On Mon, 2004-09-20 at 05:25, Patrick Caulfield wrote:
> At the cluster summit most people seedm to agree that we needed a generic,
> pluggable kernel API for cluster functions. Well, I've finally got round to
> doing something.
> The attached spec allows for plug-in cluster modules with the possibility of
> a node being a member of multiple clusters if the cluster managers allow it.
> I've seperated out the functions of "cluster manager" so they can be provided by
> different components if necessary.
> Two things that are not complete (or even started) in here are a communications
> API and a locking API.
> For the first, I'd like to leave that to those more qualified than me to do and
> for the second I'd like to (less modestly) propose our existing DLM API with the
> argument that it is a full-featured API that others can implement parts of if
> Comments please.
I read over your api and have a few comments.
Simple stuff first. The membership_node looks very similar to the SAF
interfaces, so I assume they fields mean the same. mn_member is 32bits
but it just specifies if this node is a member (1) or not (0), right?
The mni_viewnumber is 32 bits, in SAF it is 64bits. Might want it to
be 64bits. (I think nodeid should be 64bits, but SAF has it as 32bits,
so I guess it is ok).
What is mni_context?
I bit more description of these fields would be nice -- don't have to
be as verbose as SAF :)
In membership_ops, you have start_notify and notify_stop -- might want
to be consistent with the naming (either notify_start or stop_notify).
Now the more complicated stuff:
I think we need more information on how this api works and a description
of how the calls are used.
cm_attach() is used to attach to a particular cluster provider that
has been registered. Who calls cm_attach()?
I assume whoever calls cm_attach() will then be calling the ops
What is cmprivate in start_notify?
Once start_notify is called the CM module will call the callback
function whenever there is a change until notify_stop is called?
The membership_callback_routine only has "context" and "reason".
Again, what is context? What is reason?
How is the data returned? I'm guessing a struct membership_notify_info
is filled in at from the buffer passed in from start_notify, Is that
right? A bit more description here would be good.
What is the difference between get_quorate() and get_info() which
returns a struct quorum_info with qi_quorum?
Should get_quorate() and get_info() take a viewnumber so we can match
up the list of member and whether it had quorum? (it could have changed
after the callback with membership before we call get_quorum.)
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