Re: [00/17] Large Blocksize Support V3

From: Christoph Lameter
Date: Mon Apr 30 2007 - 01:31:05 EST

On Fri, 27 Apr 2007, Andrew Morton wrote:

> By misunderstanding any suggestions, misrepresenting them, making incorrect
> statements about them, by not suggesting any alternatives yourself, all of
> it buttressed by a stolid refusal to recognise that this patch has any
> costs.

That was even mentioned in the initial post.... Definitely it would
require significant changes but getting there is fairly straightforward
with the use of compound pages.

> This effectively leaves it up to others to find time to think about and to
> implement possible alternative solutions to the problems which you're
> observing.

They are working on other problems like radix tree scalability it seems.

> The altenative which is on the table (and there may be others) is
> populating pagecache with physically contiguous pages. This will fix the
> HBA problem and is much less costly in terms of maintenance and will
> improve all workloads on all machines and doesn't have the additional
> runtime costs of pagecache wastage and more memset() overhead with small
> files and it doesn't require administrator intervention.
> OTOH (yes! there are tradeoffs!) it will consume an unknown amount more
> CPU and it doesn't address the large-fs-blocksize requirement, but I don't
> know how important the latter is and given the unrelenting advocacy storm
> coming from the SGI direction I don't know how to find that out, frankly.

This is certainly a nice approach if it works and may address one
issue that motivated this patchset but it does not address all.

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