Messages in this thread | | | From | Tao Guo <> | Date | Thu, 5 Apr 2012 21:09:16 -0700 | Subject | Re: [PATCH] umem: fix up unplugging. |
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On Thu, Apr 5, 2012 at 4:51 PM, Jens Axboe <axboe@kernel.dk> wrote: > On 2012-04-04 17:58, Tao Guo wrote: >> On Wed, Apr 4, 2012 at 4:18 PM, Jens Axboe <axboe@kernel.dk> wrote: >>> On 2012-04-04 16:20, Tao Guo wrote: >>>> Hi Andrew, >>>> >>>> Thanks for your reply. >>>> >>>> Yes, without this patch the umem driver just doesn't work. >>>> It is a bug introduced by commit 7eaceaccab5f40bbfda044629a6298616aeaed50. >>>> In that patch, Jens removed the whole mm_unplug_device() function, >>>> which used to be >>>> the trigger to make umem start to work. >>> >>> Hmm indeed, that's isn't terribly useful. Why aren't we just calling >>> activate_card() on addition of a bio? >>> >> It is the original design idea, the umem driver also wants to do batch >> IO the same as >> hard disk drive to fully utilize the IO bandwidth. > > Sure, just wondering whether the benefits have been tested. But yes, it > certainly makes sense. > > Your patch looks buggy, though. What if the card is currently plugged on > another tasks plug list? You seem to assume that it can only be plugged > once. No, it will register in its own plug callback list successfully, so the unplug functions will be called separately(twice the same). -Tao > > -- > Jens Axboe >
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