Re: queue reference counting

[Nick Piggin <piggin@cyberone.com.au>]

Jens Axboe wrote:

>On Thu, Aug 07 2003, Nick Piggin wrote:
>
>>
>>Jens Axboe wrote:
>>
>>
>>>On Thu, Aug 07 2003, Pavel Machek wrote:
>>>
>>>
>>>>Hi!
>>>>
>>>>
>>>>
>>>>>I ported `subj` to 2.6.0-test2. I do not yet have idea if it works,
>>>>>but it compiles ;-).
>>>>>
>>>>>
>>>>It compiles, it event boots, but it does not seem to have much effect
>>>>:-(.
>>>>
>>>>
>>>Now that the queue reference counting is in the current bk tree, we are
>>>that much closer to real modular io schedulers. I'll post the cfq with
>>>priorities for that.
>>>
>>>
>>OK, the QUEUE_FLAG_DEAD. I assume that will be set in blk_cleanup_queue?
>>Then all remaining requests are flushed out of the queue?
>>
>>This requires that a driver must be able to continue to process requests
>>during the call to blk_cleanup_queue, and that blk_cleanup_queue might
>>block, right? Is this acceptable, or should there be an earlier call to
>>set QUEUE_FLAG_DEAD and ensure queue is flushed?
>>
>
>The plan was to add blk_shutdown_queue() to do this. And then make sure
>AS checks the dead flag and doesn't hold back any requests.
>

Sounds sensible. Just ensuring I wasn't missing out on the fun.