Re: [patch] cache pipe buf page address for non-highmem arch

[Ken Chen]

On 27 Mar 2007 17:01:01 +0200, Andi Kleen <andi@xxxxxxxxxxxxxx> wrote:
> What is the problem? You have cache misses on the the hash table
> or are the instructions really an issue on a modern CPU?

It was page_to_pfn() on numa system.  I think it's cache misses on per
node pgdat lookup with node index calculation on each pipe buffer
page.


> e.g. i out of lined virt_to_page to save space, but it could be probably
> inlined again if it was severly time critical.

That would be a problem too, though not showing up in the pipe code path.
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