] On
Behalf Of Zhang Haoyu
Sent: Tuesday, June 03, 2014 4:30 PM
To: Venkateswara Rao Nandigam; Marcus White
Cc: kvm
Subject: Re: RE: Some more basic questions..
A few additional questions:)
1. If IO to a block device goes through QEMU and not vhost, are there
data copies between kernel and user
Cc: kvm
Subject: Re: RE: Some more basic questions..
A few additional questions:)
1. If IO to a block device goes through QEMU and not vhost, are there
data copies between kernel and user mode if I do IO to a block device
or is it zero copy? Kind of related to Question (2) also.
An additional
1. If IO to a block device goes through QEMU and not vhost, are there
data copies between kernel and user mode if I do IO to a block device
or is it zero copy? Kind of related to Question (2) also.
I'm not sure, it perhaps depend on which IO mode you chose, qemu pthreads
IO, or linux AIO?
it zero copy realtively.
-Original Message-
From: kvm-ow...@vger.kernel.org [mailto:kvm-ow...@vger.kernel.org] On Behalf Of
Marcus White
Sent: Tuesday, June 03, 2014 2:50 AM
To: Zhang Haoyu
Cc: kvm
Subject: Re: Some more basic questions..
A few additional questions:)
1. If IO to a block
A few additional questions:)
1. If IO to a block device goes through QEMU and not vhost, are there
data copies between kernel and user mode if I do IO to a block device
or is it zero copy? Kind of related to Question (2) also.
An additional copy will be avoided only by using vhost, so if you are
Sent: Tuesday, June 03, 2014 4:30 PM
To: Venkateswara Rao Nandigam; Marcus White
Cc: kvm
Subject: Re: RE: Some more basic questions..
A few additional questions:)
1. If IO to a block device goes through QEMU and not vhost, are there
data copies between kernel and user mode if I do IO to a block
A few additional questions:)
1. If IO to a block device goes through QEMU and not vhost, are there
data copies between kernel and user mode if I do IO to a block device
or is it zero copy? Kind of related to Question (2) also.
An additional copy will be avoided only by using vhost, so if you are
...@vger.kernel.org [mailto:kvm-ow...@vger.kernel.org] On Behalf
Of Zhang Haoyu
Sent: Tuesday, June 03, 2014 4:30 PM
To: Venkateswara Rao Nandigam; Marcus White
Cc: kvm
Subject: Re: RE: Some more basic questions..
A few additional questions:)
1. If IO to a block device goes through QEMU and not vhost
A few additional questions:)
1. If IO to a block device goes through QEMU and not vhost, are there
data copies between kernel and user mode if I do IO to a block device
or is it zero copy? Kind of related to Question (2) also.
2. A related question to (1), is the QEMU process separate from the
A few additional questions:)
1. If IO to a block device goes through QEMU and not vhost, are there
data copies between kernel and user mode if I do IO to a block device
or is it zero copy? Kind of related to Question (2) also.
I'm not sure, it perhaps depend on which IO mode you chose, qemu
On Mon, Jun 2, 2014 at 8:43 PM, Zhang Haoyu zhan...@sangfor.com wrote:
A few additional questions:)
1. If IO to a block device goes through QEMU and not vhost, are there
data copies between kernel and user mode if I do IO to a block device
or is it zero copy? Kind of related to Question (2) also.
Thanks Zhang and Venkateshwara, some more follow up questions below:)
1. Does -realtime mlock=on allocate all the memory upfront and keep it
for the VM, or does it just make sure the memory that is allocated
within the guest is not swapped out under host memory pressure?
“-realtime mlock=on”
1. How can I ensure that memory for the a guest is available and reserved?
In other words, I bring up a Linux VM which has 4G allocated, I want to make
sure it has all the 4G available right away.
I saw references to balloon driver, it seemed like that was more for dynamic
memory exchange
Hello,
Some more basic questions..
1. How can I ensure that memory for the a guest is available and
reserved? In other words, I bring up a Linux VM which has 4G
allocated, I want to make sure it has all the 4G available right away.
I saw references to balloon driver, it seemed like that
Thanks Zhang and Venkateshwara, some more follow up questions below:)
1. Does -realtime mlock=on allocate all the memory upfront and keep it
for the VM, or does it just make sure the memory that is allocated
within the guest is not swapped out under host memory pressure?
2. I notice on a 4G
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