> Our driver using the following flags in its cb_ops structure:
> ( D_NEW | D_MP | D_MTOUTEPERIM | D_MTOCEXCL ).
> I understand that this set of flags will make the open & close routines
> synchronous.
The open and close routines are *always* synchronous. D_MTOCEXCL makes
sure there's only one thread in open or close at a time across all the
instances of the driver in the system (basically, it forces the outer
perimeter to be entered exclusively for those entrypoints). BTW, the
D_NEW flag above does nothing (it expands to 0x0) and should be removed.
> My question is - do I need to add the D_MTPUTHSARED, D_MTPERQ, and
> _D_MTSVCSHARED flags to make sure read and write queue put & service
> routines can run concurrently ?
No -- D_MP does that already. For an inner perimeter, you have four
basic choices:
* D_MP: effectively no inner perimeter.
* D_MTPERQ: inner perimeter around each queue.
* D_MTQPAIR: inner perimeter around each queuepair.
* D_MTPERMOD: inner perimeter around all queuepairs.
Since the inner perimeter is always exclusively by default, D_MP is the
highest level of concurrency, and flags like D_MTPUTSHARED make no sense
with it. You can approximate D_MP to some degree by combining coarser
perimeters with e.g. D_MTPUTSHARED and the like, but there's no reason to
do that unless you have a specific reason to not be D_MP. As an aside:
_D_MTSVCSHARED is not a public interface (hence the leading underscore).
Do not use it.
Hope this helps,
--
meem
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