Re: [RFC] hw/arm/smmuv3: add device properties to disable cached iotlb

[Peter Maydell]

On Wed, 4 Aug 2021 at 09:41, chenxiang <chenxiang66@hisilicon.com> wrote:
>
> From: Xiang Chen <chenxiang66@hisilicon.com>
>
> It splits invalidations into ^2 range invalidations in the patch
> 6d9cd115b(" hw/arm/smmuv3: Enforce invalidation on a power of two range").
> So for some scenarios such as the size of invalidation is not ^2 range
> invalidation, it costs more time to invalidate.
> Currently smmuv3_translate is rarely used (i only see it is used when
> binding msi), so i think maybe we can disable cached iotlb to promote
> efficiency of invalidation. So add device property disable_cached_iotlb
> to disable cached iotlb, and then we can send non-^2 range invalidation
> directly.
> Use tool dma_map_benchmark to have a test on the latency of unmap,
> and we can see it promotes much on unmap when the size of invalidation
> is not ^2 range invalidation (such as g = 7/15/31/511):


Hi. Can you send all patches to the qemu-devel list, please (you can
cc qemu-arm if you like)? The automated patch-handling tools and some
developers only read qemu-devel.
https://wiki.qemu.org/Contribute/SubmitAPatch has some more detail
on sending patches.

thanks
-- PMM