[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] the arm cache coherency cluster "v2"
From: |
Andrew Jones |
Subject: |
Re: [Qemu-devel] the arm cache coherency cluster "v2" |
Date: |
Wed, 18 Mar 2015 20:18:20 +0100 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
On Wed, Mar 18, 2015 at 03:08:20PM -0400, Andrew Jones wrote:
> In reply to this message I'll send two series' one for KVM and
> one for QEMU. The two series' are their respective component
> complements, and attempt to implement cache coherency for arm
> guests using emulated devices, where the emulator (qemu) uses
> cached memory for the device memory, but the guest uses
> uncached - as device memory is generally used. Right now I've
> just focused on VGA vram.
>
> This approach is the "MADV_UNCACHED" type that Paolo suggested.
> This type of approach could also be described as "make userspace's
> memory access type match the expected access type of the guest",
> and Mario has suggested using a memory driver, which could have
> the same result.
>
> The coming series' is inspired by both Paolo's and Mario's
> suggestions, but it uses a kvm memslot flag, rather than an
> madvise flag, and thus for the memory driver, it's just KVM.
>
> See the thread
>
> https://lists.gnu.org/archive/html/qemu-devel/2015-03/msg01254.html
>
> for some more background.
>
> Thanks in advance for comments.
>
> drew
I forgot to mention that I've done some light testing with this.
It seems to work, and without (to eye) noticeable performance
degradation.
Thanks,
drew
- [Qemu-devel] [RFC PATCH 3/3] arm/arm64: KVM: implement KVM_MEM_UNCACHED, (continued)