[illumos-Developer] initial review: bombproof taskq dispatch

[Albert Lee]

On Wed, May 4, 2011 at 8:11 PM, Garrett D'Amore <garrett at nexenta.com> wrote:
> 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. :-)
>

We have an effectively unlimited queue length here, given that we
ignore taskq_{min,max}alloc. Those values are specified at
taskq_create separately from the thread count, though.

-Albert