On 4 August 2014 11:23, Alex Bennée <alex.ben...@linaro.org> wrote: > Peter Maydell writes: >> So: >> * there's clearly a big perf win to be had here >> * this patchset gives us that for 4K pages on AArch64 >> * but it doesn't help for 4K pages on AArch32 (really >> common) > > Well for the AArch32 profile if you ran under qemu-system-aarch64 you > would be OK surely?
Yes, but that's pretty non-obvious, and also it doesn't make much sense to the user to say "these 32 bit CPUs should be run under qemu-system-aarch64 but these other ones should be under qemu-system-arm". >> * and it's not going to be good for 64K pages on AArch64 >> either (which I suspect will not be a rare choice) > > Does the kernel already use 64k pages for it's code? There's a config option, which will cause it to use 64K pages for everything including userspace. (There's also 16K pages but I forget if Linux has support for those.) I think the kernel can also use 64K pages in some cases even in a 4K page config, but I don't know the details. thanks -- PMM
