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Re: [Qemu-devel] [RFC PATCH] include/exec/cpu-defs.h: try and make SoftM
Re: [Qemu-devel] [RFC PATCH] include/exec/cpu-defs.h: try and make SoftMMU page size match target
Mon, 10 Jul 2017 15:35:34 +0100
On 10 July 2017 at 15:28, Alex Bennée <address@hidden> wrote:
> While the SoftMMU is not emulating the target MMU of a system there is
> a relationship between its page size and that of the target. If the
> target MMU is full featured the functions called to re-fill the
> entries in the SoftMMU entries start moving up the perf profiles. If
> we can we should try and prevent too much thrashing around by having
> the page sizes the same.
> Ideally we should use TARGET_PAGE_BITS_MIN but that potentially
> involves a fair bit of #include re-jigging so I went for 10 bits (1k
> pages) which I think is the smallest of all our emulated systems.
The figures certainly show an improvement, but it's not clear
to me why this is related to the target's page size rather than
just being a "bigger is better" kind of thing?