Re: [Qemu-devel] [PATCH v2 0/5] AArch64 TLB performance improvements

[Peter Maydell]

On 1 August 2014 17:06, Peter Maydell <address@hidden> wrote:
> I'm taking the first two of these into target-arm.next because
> they're obvious standalone bugfixes. I need to think about the
> last three a bit more: I dislike just dropping the ARMv5 CPUs
> from qemu-system-aarch64, it's kind of arbitrary.

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)
 * and it's not going to be good for 64K pages on AArch64
   either (which I suspect will not be a rare choice)

So I think it would be good if we investigated the degree
of difficulty in improving QEMU's TLB code so it isn't just
"one TLB entry size with larger pages a bolt-on which we
hope people don't actually use" first, before we just disable
all the v5 CPUs.

thanks
-- PMM