[illumos-Developer] initial review: bombproof taskq dispatch

[Garrett D'Amore]

On Wed, 2011-05-04 at 18:52 -0500, Jason King wrote:

> 
> 
> 
> With the preface that a number of these questions are also partially
> for my own edification, so these might be more than a bit ignorant :)
> 
> 
> This change would seem to ignore any limits on the number of threads
> for a taskq (or rather it appears you could create more static
> taskq_ent_t's than the limit for the taskq & dispatch all of them).
> A lot of the logic within taskq_dispatch seems to depend on this limit
> (and in fact the taskq itself allocates max_nthreads # of kthread_t
> structures).  Is this correct?

Nothing I've done touches the threading stuff... the only thing is that
my stuff is totally incompatible with dynamic taskqs.  Folks using
dynamic taskqs don't want this prealloc behavior anyway, because dynamic
taskq dispatch might actually create whole threads. :-)

> 
> 
> Since the ddi_taskq_* functions are just a thin wrapper around taskq's
> are there any plans to extend this for the ddi as well?

We could do that, but it would mean exposing taskq_ent_t, or at least
the size/alignment considerations for it.  I consider that a future
idea, once we get some more experience with this.

	- Garrett