Re: [00/17] Large Blocksize Support V3

From: Nick Piggin
Date: Fri Apr 27 2007 - 05:47:01 EST


William Lee Irwin III wrote:
On Fri, Apr 27, 2007 at 01:38:30AM +1000, Nick Piggin wrote:

Or good grounds to increase the sg limit and push for io controller
manufacturers to do the same. If we have a hack in the kernel that
mostly works, they won't.


On Fri, Apr 27, 2007 at 01:38:30AM +1000, Nick Piggin wrote:

Page colouring was always rejected, and lots of people who knew
better got upset because it was the only way the hardware would go
fast...


Yes, stunning wisdom there. Reject the speedups.

Yeah, that's how lots of people felt. But there is a good argument
to do just that.


On Fri, Apr 27, 2007 at 01:38:30AM +1000, Nick Piggin wrote:

You could put it that way. Or that it is wrong because of the
fragmenatation problem. Realise that it is somewhat fundamental
considering that it is basically an unsolvable problem with our
current kernel assumptions of unconstrained kernel allocations and
a 1:1 kernel mapping.


Depends on what you consider a solution. A broadly used criterion is
that improves performance significantly in important usage cases.

My criterion is that you are not suddenly unable to access your
filesystem because you cannot allocate a higher order page.

--
SUSE Labs, Novell Inc.
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