Re: [Lsf-pc] [LSF/MM TOPIC] really large storage sectors - goingbeyond 4096 bytes

From: Andrew Morton
Date: Wed Jan 22 2014 - 14:50:18 EST

On Wed, 22 Jan 2014 11:30:19 -0800 James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> wrote:

> But this, I think, is the fundamental point for debate. If we can pull
> alignment and other tricks to solve 99% of the problem is there a need
> for radical VM surgery? Is there anything coming down the pipe in the
> future that may move the devices ahead of the tricks?

I expect it would be relatively simple to get large blocksizes working
on powerpc with 64k PAGE_SIZE. So before diving in and doing huge
amounts of work, perhaps someone can do a proof-of-concept on powerpc
(or ia64) with 64k blocksize.

That way we'll at least have an understanding of what the potential
gains will be. If the answer is "1.5%" then poof - go off and do
something else.

(And the gains on powerpc would be an upper bound - unlike powerpc, x86
still has to fiddle around with 16x as many pages and perhaps order-4

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