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Re: [dm-devel] New -udm?



Mike Christie wrote:
Lars Marowsky-Bree wrote:

On 2005-04-10T18:14:44, Dave Olien <dmo osdl org> wrote:


You're correct.  I'll rewrite it on Thursday this week.
I'll use the same methods Lars used in the dm-emc.c



Note that dm-emc.c also would need to pre-allocate it's requests, but doesn't right now :/

Pre-allocating the requests sucks: Either we pre-allocate for _every_
path we might potentially need to send the request down on, or fix up
the request for the path we sent it down on (which would require us to
use internal knowledge about the req structs we're not supposed to
have).


what is wrong with what you have now where you utilize the queue/path's mempool by doing a blk_get_request with GFP_WAIT?

or were you talking about the page for data backing which does not have a mempool like the bios (not per queue though) and requests.


Is that "fix up the
request..." comment meaning that you do not like to access the request structure for that code, or was it meaning that you have one request that is shared across paths and it needs to be cleaned up for reuse.

I think the hw_handlers setting up the requests is not so fun. Maybe the block layer scsi_ioctl code could be reworked a little so that it could set some of that up for us since it is very similar. My hw handler was basically cutting and pasting of that code with some large simplifcations. I am working on a Target Port Group handler that is again cutting and pasting more code.


Good solutions solicited ;-)



Sincerely, Lars Marowsky-Brée <lmb suse de>



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