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

Ken Chen
2007-03-27T18:06:31Z

On 27 Mar 2007 17:01:01 +0200, Andi Kleen <andi@firstfloor.org> 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.