[dm-devel] [PATCH] dm-mpath: push back requests instead of queueing
Hannes Reinecke
hare at suse.de
Tue Nov 12 10:17:43 UTC 2013
On 11/12/2013 11:00 AM, Junichi Nomura wrote:
> On 11/12/13 18:05, Hannes Reinecke wrote:
[ .. ]
>> We _could_ optimize this in __switch_pg(), to call pgpath_busy()
>> when selecting the paths. But that should be done by the path selector.
>> So for that we would need to separate the functionality of the
>> path selector and __switch_pg; currently it's unclear whether
>> we need to call pgpath_busy() in __switch_pg or not.
>
> There is no need to call pgpath_busy in __switch_pg.
>
> If we call __pgpath_busy() in map function, I think it's here:
>
> if (pgpath) {
> + if (__pgpath_busy(pgpath))
> + r = DM_MAPIO_REQUEUE;
> else if (pg_ready(m)) {
> ... // remap
> r = DM_MAPIO_REMAPPED;
> } else {
> __pg_init_all_paths(m);
> r = DM_MAPIO_REQUEUE;
> }
> ...
>
Which is what I had in mind.
> or in a path selector.
>
Hmm. The path selector might have a reason for selecting this
particular path. So I'd prefer not to have it in there.
Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
hare at suse.de +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)
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