On 19:12 Tue 31 Mar , Ralf Baechle wrote: > On Wed, Apr 01, 2009 at 12:54:12AM +0800, Zhang Le wrote: > > > > > Linux on Loongson 2E and 2F uses 16k page size to avoid cache alias problem, too. > > > > However, I haven't encountered any problem on Linux kernel itself due to 16k page > > > > size. > > > > > > > > Anyway, I am not 100% familiar with Loongson patches, so I am not sure whether > > > > the page size problem is already been taken care of in the patch. If you are > > > > interested to find out yourself, you can get the whole source here: > > > > http://repo.or.cz/w/linux-2.6/linux-loongson.git > > > > > > I've got a report that Fulong is currently only working with 16k pages. So > > > 4k is no longer the bullet proof choice for all cases :) > > > > Yes, at least from what I can tell. > > I have tried 4k before, because I heard someone told me the aliasing problem > > already can be taken care by software, namely Linux. But as it turned out, 16k > > is still necessary for the Loongson boxes to function properly. > > Linux knows how to handle aliasing caches - the vast majority of MIPS > systems have aliasing caches and are running at 4k page size. So the > issue is Loongson-specific. This might be due to processor detection > not detecting the cache size, cache line size, number of ways correctly > or because loongson's caches has some unusual cache properties which the > Linux kernel is not designed to handle yet. > > Btw, I just noticed that there is no > arch/mips/include/asm/mach-lemote/cpu-feature-overrides.h which is going > to impact code size and performance. Thanks for the reminder. I didn't know it before. I am gonna take a look. Zhang, Le http://zhangle.is-a-geek.org
