Re: [00/17] Large Blocksize Support V3

Nick Piggin
2007-04-26T07:57:27Z

Christoph Lameter wrote:
> On Thu, 26 Apr 2007, Nick Piggin wrote:
>
>
>>Yeah. IMO anti-fragmentation and defragmentation is the hack, and we
>>should stay away from higher order allocations whenever possible.
>
>
> Right and we need to create series of other approaches that we then label
> "non-hack" to replace it.

I don't understand? We're talking about several utterly different designs
to approach these problems. You don't agree that one might be better than
another?

>>Hardware is built to handle many small pages efficintly, and I don't
>>understand how it could be an SGI-only issue. Sure, you may have an
>>order of magnitude or more memory than anyone else, but even my lowly
>>desktop _already_ has orders of magnitude more pages than it has TLB
>>entries or cache -- if a workload is cache-nice for me, it probably
>>will be on a 1TB machine as well, and if it is bad for the 1TB machine,
>>it is also bad on mine.
>
>
> There have been numbers of people that have argued the same point. Just
> because we have developed a way of thinking to defend our traditional 4k
> values does not make them right.
>
>
>>If this is instead an issue of io path or reclaim efficiency, then it
>>would be really nice to see numbers... but I don't think making these
>>fundamental paths more complex and slower is a nice way to fix it
>>(larger PAGE_SIZE would be, though).
>
>
> The code paths can stay the same. You can switch CONFIG_LARGE pages off
> if you do not want it and it is as it was.

That isn't a good reason to merge something. If you don't have numbers then
that just seems incredible.

> If you would have a look the patches: The code is significantly cleanup
> and easier to read.

Cleanups are fine.

--
SUSE Labs, Novell Inc.