Il giorno 23 gen 2017, alle ore 18:42, Jens Axboe [off-list ref] ha =

scritto:

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On 01/23/2017 10:04 AM, Paolo Valente wrote:

quoted

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quoted

Il giorno 18 gen 2017, alle ore 17:21, Jens Axboe [off-list ref] ha =

scritto:

quoted

quoted

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On 01/18/2017 08:14 AM, Paolo Valente wrote:

quoted

according to the function blk_mq_sched_put_request, the
mq.completed_request hook seems to always be invoked (if set) for a
request for which the mq.put_rq_priv is invoked (if set).

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Correct, any request that came out of blk_mq_sched_get_request()
will always have completed called on it, regardless of whether it
had IO started on it or not.
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It seems that some request, after being dispatched, happens to have =

no

quoted

mq.put_rq_priv invoked on it now or then.  Is it expected?  If it is,
could you point me to the path through which the end of the life of
such a request is handled?

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I'm guessing that's a flush request. I added RQF_QUEUED to check for
that, if RQF_QUEUED is set, you know it has come from your get_request
handler.
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Exactly, the completion-without-put_rq_priv pattern seems to occur
only for requests coming from the flusher, precisely because they have
the flag RQF_ELVPRIV unset.  Just to understand: why is this flag
unset for these requests, if they do have private elevator (bfq)
data attached?  What am I misunderstanding?

Just to be certain: this should be the only case where the
completed_request hook is invoked while the put_rq_priv is not, right?

Thanks,
Paolo

I'm assuming that is it, let me know.
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Jens Axboe
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