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    SubjectRe: [RFC, PATCH] cfq-iosched: remove redundant queuing detection code
    Jens Axboe <> writes:

    > On Tue, Nov 10 2009, Corrado Zoccolo wrote:
    >> The core block layer already has code to detect presence of command
    >> queuing devices. We convert cfq to use that instead of re-doing the
    >> computation.
    > There's is the major difference that the CFQ variant is dynamic and the
    > block layer one is not. This change came from Aaron some time ago IIRC,
    > see commit 45333d5. It's a bit of a chicken and egg problem.

    Really? blk_dequeue_request sure looks like it updates things
    dynamically, but only one way (not queueing -> queueing). Would it make
    sense to just put CFQ's logic into the block layer so that everyone uses
    the same implementation? It makes little sense to have two notions of
    whether or not queueing is supported for a device.


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