Messages in this thread | | | Date | Fri, 5 Dec 2014 12:31:17 +0000 | From | Catalin Marinas <> | Subject | Re: [PATCH] arm64: Enable CONFIG_COMPAT also for 64k page size |
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On Fri, Dec 05, 2014 at 12:24:49PM +0000, Arnd Bergmann wrote: > On Friday 05 December 2014 11:05:07 Catalin Marinas wrote: > > > > > Should we add support for 64k-pages in the arm32 kernel as well now? > > > > 32-bit LPAE doesn't support 64K pages but IIRC the classic MMU does > > (though I have to check whether it was optional). But it's not feasible > > to enable this in a 32-bit environment because of the memory wasted with > > large pages (on average 32KB per mapped file, possibly even more if you > > have lots of small files). > > That sounds like a tradeoff that some users might be willing to make. > > I remember that with ps3-linux, a lot of people wanted to enable 64k-pages > because the Cell processor has such a small number of TLB entries (256 or > 1024), but Linux only has around 200MB of memory available. I believe > there are arm32 machines with more RAM and fewer TLBs.
I've heard that the WD MyCloud NAS (Cortex-A9 based) moved to 64K pages and they rebuilt the filesystem (which annoyed some people that were previously installing Debian packages directly, they now need recompilation).
-- Catalin
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