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    SubjectRe: [RFC V2 PATCH 2/5] cfq-iosched: preparation to handle multiple service trees
    Corrado Zoccolo <> writes:

    > Hi Jeff,
    > On Wed, Oct 21, 2009 at 5:31 PM, Jeff Moyer <> wrote:
    >> Corrado Zoccolo <> writes:
    >>> We embed a pointer to the service tree in each queue, to handle multiple
    >>> service trees easily.
    >>> Service trees are enriched with a counter.
    >>> cfq_add_rq_rb is invoked after putting the rq in the fifo, to ensure
    >>> that all fields in rq are properly initialized.
    >>> @@ -115,6 +116,9 @@ struct cfq_queue {
    >>>       unsigned short ioprio_class, org_ioprio_class;
    >>>       pid_t pid;
    >>> +
    >>> +     struct cfq_rb_root *service_tree;
    >>> +     struct cfq_io_context *cic;
    >>>  };
    >> This change worries me.  For async queues, there is not a 1:1 mapping
    >> between cfqq and cic.
    > Currently, I need it only for sync queues. And it is used only to
    > determine if a queue is seeky, so if we can mark it in the queue
    > instead of the cic, this will not be needed any more.

    Ah ha! I have the same requirement for breaking the queues apart, so I
    think this won't be an issue.

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      Last update: 2009-10-21 18:29    [W:0.021 / U:6.800 seconds]
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