Re: sg driver and Fedora Core 2

Jeff Garzik
2004-05-29T17:58:26Z

James Bottomley wrote:
> On Sat, 2004-05-29 at 12:27, Jeff Garzik wrote:
>
>>Really what needs to happen is a generic userland tap attaches to a
>>chrdev, issues an ioctl(2) to attach to a request_queue, and then does
>>read(2)/write(2)/mmap(2) to communicate with the request_queue.
>>
>>:)
>>
>>Call it /dev/bsg, or somesuch.
>
>
> Well, this touches on something else I'm thinking about: lazy
> attachment. In multi thousand disc environments, you don't want us
> wasting resources allocating a queue and reading a partition table for
> all of them; you really only want to do that for the devices you're
> actually going to use. Once we have this, I think dual attachment will
> be a dead issue.

Regardless of lazy attachment, request_queues need to support multiple
simultaneous producers of struct request's.

Jeff