Re: [RFC PATCHSET] workqueue: implement concurrency managed workqueue

Stefan Richter
2009-10-02T12:46:48Z

Tejun Heo wrote:
> David Howells wrote:
>> Sounds interesting as a replacement for slow-work. Some thoughts for you:
>>
>> The most important features of slow-work are:
>>
>> (1) Work items are not re-entered whilst they are executing.
>>
>> (2) The slow-work facility keeps references on its work items by asking the
>> client to get and put on the client's refcount.
>>
>> (3) The slow-work facility can create a lot more threads than the number of
>> CPUs on a system, and the system doesn't grind to a halt if they're all
>> taken up with long term I/O (performing several mkdirs for example).
>>
>> I think you have (1) and (3) covered, but I'm unsure about (2).
>
> Given that slow-work isn't being used too extensively yet, I was
> thinking whether that part could be pushed down to the caller. Or, we
> can also wrap work and export an interface which supports the get/put
> reference.

BTW, not only slow-work users need reference counting, many existing
regular workqueue users could use it as well. (Well, I guess I stated
the obvious.) Currently we have local wrappers for that like these ones:
http://lxr.linux.no/#linux+v2.6.31/drivers/firewire/core-card.c#L212
http://lxr.linux.no/#linux+v2.6.31/drivers/firewire/sbp2.c#L838
--
Stefan Richter
-=====-==--= =-=- ---=-