[dm-devel] 2.6.10-rc1-udm1: multipath work in progress
Alasdair G Kergon
agk at redhat.com
Tue Nov 2 15:50:43 UTC 2004
On Tue, Nov 02, 2004 at 03:51:03PM +0100, Stefan Bader wrote:
> Personally I would rather see path information moving into the path
> selector
We need some concrete examples of what information is missing and
how other sorts of path selectors would benefit from it.
> There are even some fields and functions in dm-mpath.c
> (current_count) that are rather specific to a selector.
That's a generic optimisation - you normally don't want to be
recalculating which path to use for every single I/O - choose
a path, then send the next X I/O down it before reassessing
which to use.
> For path selectors: what about per selector arguments?
Probably, but first we need some concrete examples of arguments that
can't be per-path.
> For example the round-robin could take the number of io operations
> before switching to the next path:
> round-robin 1 1000 2 1 7:1 1 7:2
It already does, as a more-flexible per-path argument.
Alasdair
--
agk at redhat.com
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