Re: [PATCH 00/24] ide-tape: remove pipelined mode operation

From: Borislav Petkov
Date: Sat Mar 01 2008 - 10:45:52 EST


On Sat, Mar 01, 2008 at 10:55:18AM +0100, Jens Axboe wrote:
> On Sat, Mar 01 2008, Borislav Petkov wrote:
> > Hi Bart,
> >
> > here's the 1st draft of the pipeline removal series. As the diffstat below openly
> > states it, a lot of code got removed - even more than the cleanup series we did
> > earlier. There are several issues that we need to address concerning these
> > patches:
> >
> > 1. only compile-tested since i don't have the hardware, i.e. longer -mm brewing is
> > advisable the least.
> >
> > 2. I have left the tape->merge_stage buffer structure along with its
> > alloc/free functions intact for now, for simplicity. The next step would be
> > to go and carefully audit the code and then remove that last piece
> > too and use allocations on the stack instead. I guess we still expect
> > Jens's response on whether blk_{get,put}_request is the way to go here.
> >
> > Jens?
>
> Hm, I have not seen any questions regarding this directed my way :-)
> Please point me to the original question and I'll take a look at it.

Hi Jens,

sorry but maybe we weren't that explicit, here's a pointer to the relevant
thread: http://www.mail-archive.com/linux-ide@xxxxxxxxxxxxxxx/msg15541.html. It
boils down to removing the statically allocated arrays of buffers for pc and rq
structs in ide-floppy and ide-tape, and using GFP_ATOMIC stack memory instead.
Bart's idea was to even go a step further and even avoid allocation errors in
out-of-mem situations by reusing requests from the request queue but wasn't sure
whether this'll fly and wanted to run it by you...

Thanks.

--
Regards/Gruß,
Boris.
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