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    SubjectRe: What am I doing wrong? submit_bio() suddenly stops working...
    On Thu, Oct 21, 2010 at 08:59:46AM +0200, Jens Axboe wrote:
    > I don't see anything immediately wrong with your approach. I suspect
    > we'll need to see sysrq-t traces of the relevant processes to make a
    > more educated guess!

    I've uploaded a trace output that includes the sysrq-t trace, but I
    don't think it shows anything interesting. We're not hanging on any
    kind of loack as near as I can tell. It looks like
    __generic_make_request() is calling q->make_request_fn(), and this is
    returning without actually doing anything.

    In this trace, I added a patch to prove that __generic_make_request()
    is calling __make_request (I wasn't sure what q->make_request_fn was
    indirecting to, so I added a brute force lookup to make sure I
    understood what was going on), but at one point, it just starts
    queuing the request, and it enters cfq, but the request never gets
    dispatched out. Maybe this is a failure of the plugging/unplugging

    I guess I can start putting in more brute-force printk's inside
    __make_request and inside the cfq scheduler to try to understand what
    is going on, but I'm really guessing at this point.

    If you have any suggestions about more elegant ways of figuring what
    is happening, please do let me know....

    - Ted

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      Last update: 2010-10-21 18:59    [W:0.022 / U:2.344 seconds]
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