From: Gleb Natapov <gleb@redhat.com>
To: Jan Kiszka <jan.kiszka@web.de>
Cc: kvm <kvm@vger.kernel.org>, qemu-devel <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] qemu vs. kvm: When to flush the coalesced mmio buffer?
Date: Mon, 3 Jan 2011 14:25:08 +0200 [thread overview]
Message-ID: <20110103122507.GA23389@redhat.com> (raw)
In-Reply-To: <4D21BCF4.6020904@web.de>
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.
WARNING: multiple messages have this Message-ID (diff)
From: Gleb Natapov <gleb@redhat.com>
To: Jan Kiszka <jan.kiszka@web.de>
Cc: qemu-devel <qemu-devel@nongnu.org>, kvm <kvm@vger.kernel.org>
Subject: Re: [Qemu-devel] qemu vs. kvm: When to flush the coalesced mmio buffer?
Date: Mon, 3 Jan 2011 14:25:08 +0200 [thread overview]
Message-ID: <20110103122507.GA23389@redhat.com> (raw)
In-Reply-To: <4D21BCF4.6020904@web.de>
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.
next prev parent reply other threads:[~2011-01-03 12:25 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-03 12:11 qemu vs. kvm: When to flush the coalesced mmio buffer? Jan Kiszka
2011-01-03 12:11 ` [Qemu-devel] " Jan Kiszka
2011-01-03 12:25 ` Gleb Natapov [this message]
2011-01-03 12:25 ` Gleb Natapov
2011-01-03 12:32 ` Avi Kivity
2011-01-03 12:32 ` [Qemu-devel] " Avi Kivity
2011-01-03 12:34 ` Jan Kiszka
2011-01-03 12:34 ` [Qemu-devel] " Jan Kiszka
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