From: Gleb Natapov <gleb@redhat.com>
To: Avi Kivity <avi@redhat.com>
Cc: Jan Kiszka <jan.kiszka@siemens.com>,
Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>,
Marcelo Tosatti <mtosatti@redhat.com>,
LKML <linux-kernel@vger.kernel.org>, KVM <kvm@vger.kernel.org>
Subject: Re: [PATCH] KVM: x86: fix vcpu->mmio_fragments overflow
Date: Mon, 22 Oct 2012 15:05:58 +0200 [thread overview]
Message-ID: <20121022130558.GV29310@redhat.com> (raw)
In-Reply-To: <508543DE.3080504@redhat.com>
On Mon, Oct 22, 2012 at 03:02:22PM +0200, Avi Kivity wrote:
> On 10/22/2012 03:01 PM, Gleb Natapov wrote:
>
> >> It's time where the guest cannot take interrupts, and time in a high
> >> priority guest thread that is spent processing low guest priority requests.
> >>
> > Proposed fix has exactly same issue. Until all data is transfered to
> > userspace no interrupt will be served.
>
> For mmio_fragments that is okay. It's the same guest instruction, and
> it's still O(1).
>
> It's not okay for general mmio coalescing.
>
Ah, so optimizing mmio_fragments transmission to userspace using
dedicated coalesced MMIO buffer should be fine then. Unfortunately,
since we cannot use shared ring buffer that exists now, this is too much
work for small gain that only new QEMU will be able to enjoy.
--
Gleb.
next prev parent reply other threads:[~2012-10-22 13:06 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-19 7:37 [PATCH] KVM: x86: fix vcpu->mmio_fragments overflow Xiao Guangrong
2012-10-19 7:39 ` [PATCH] emulator test: add "rep ins" mmio access test Xiao Guangrong
2012-11-01 0:05 ` Marcelo Tosatti
2012-10-22 9:16 ` [PATCH] KVM: x86: fix vcpu->mmio_fragments overflow Gleb Natapov
2012-10-22 11:09 ` Xiao Guangrong
2012-10-22 11:23 ` Gleb Natapov
2012-10-22 11:35 ` Jan Kiszka
2012-10-22 11:43 ` Gleb Natapov
2012-10-22 11:45 ` Jan Kiszka
2012-10-22 12:18 ` Avi Kivity
2012-10-22 12:45 ` Jan Kiszka
2012-10-22 12:53 ` Gleb Natapov
2012-10-22 12:55 ` Jan Kiszka
2012-10-22 12:58 ` Avi Kivity
2012-10-22 13:05 ` Jan Kiszka
2012-10-22 13:08 ` Gleb Natapov
2012-10-22 13:25 ` Jan Kiszka
2012-10-22 14:00 ` Gleb Natapov
2012-10-22 14:23 ` Jan Kiszka
2012-10-22 15:36 ` Avi Kivity
2012-10-22 12:58 ` Gleb Natapov
2012-10-22 12:55 ` Avi Kivity
2012-10-22 13:01 ` Gleb Natapov
2012-10-22 13:02 ` Avi Kivity
2012-10-22 13:05 ` Gleb Natapov [this message]
2012-10-22 12:56 ` Avi Kivity
2012-10-22 13:58 ` Avi Kivity
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