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Re: [Qemu-devel] qemu vs. kvm: When to flush the coalesced mmio buffer?
From: |
Gleb Natapov |
Subject: |
Re: [Qemu-devel] qemu vs. kvm: When to flush the coalesced mmio buffer? |
Date: |
Mon, 3 Jan 2011 14:25:08 +0200 |
On Mon, Jan 03, 2011 at 01:11:32PM +0100, Jan Kiszka wrote:
> Hi again,
>
> another subtle difference between qemu-kvm and upstream:
>
> When we leave the guest for an IO window (KVM_RUN returns EINTR or
> EAGAIN), we call kvm_flush_coalesced_mmio_buffer in qemu-kvm but not in
> upstream. When version is better? I can't find any rationales in both
> git logs.
>
Since coalesced mmio is used to prevent unnecessary exits to userspace
if vcpu thread is already in userspace why not flush coalesced mmio
buffer?
--
Gleb.