Messages in this thread | | | Subject | Re: DRM lock ordering fix series | From | Peter Zijlstra <> | Date | Sat, 28 Mar 2009 02:29:59 +0100 |
| |
On Sat, 2009-03-28 at 01:58 +0100, Peter Zijlstra wrote:
> > OK. I'm not too excited here -- 10% of 2% of the CPU time doesn't get > > me to the 10% loss that the slow path added up to. Most of the cost is > > in k{un,}map_atomic of the returned pages. > > Also note that doing large gup() with gup_fast() will be undesirable due > to it disabling IRQs. So iterating say several MB worth of pages will > hurt like crazy. Currently all gup_fast() users do a single page lookup.
Also, what's this weird facination with 32bit, can you even buy a 32bit only cpu these days?
| |