WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-users

RE: [Xen-users] What's the different for "dom0_max_vcpus=4dom0_vcpus_pin

To: "lei yang" <yanglei.fage@xxxxxxxxx>, "Xen Mailing List" <xen-users@xxxxxxxxxxxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-users] What's the different for "dom0_max_vcpus=4dom0_vcpus_pin" and "dom0_max_vcpus=4" ?
From: "Robert Dunkley" <Robert@xxxxxxxxx>
Date: Fri, 21 May 2010 13:02:45 +0100
Cc:
Delivery-date: Fri, 21 May 2010 05:05:23 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
List-help: <mailto:xen-users-request@lists.xensource.com?subject=help>
List-id: Xen user discussion <xen-users.lists.xensource.com>
List-post: <mailto:xen-users@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/mailman/listinfo/xen-users>, <mailto:xen-users-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-users>, <mailto:xen-users-request@lists.xensource.com?subject=unsubscribe>
References: <AANLkTik4TnkY-uGfhW5sbPwG5U1msw_eVt5X1j0IDdBD@xxxxxxxxxxxxxx>
Sender: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
Thread-index: Acr4k0na6Y6Xny+aT16NyQ9pgQV+9QASWyMg
Thread-topic: [Xen-users] What's the different for "dom0_max_vcpus=4dom0_vcpus_pin" and "dom0_max_vcpus=4" ?

Hi Lei,

 

 

Q1: The pin is needed to lock Dom0 to cores 0 & 1.

 

Q2: It means 4 vcpus are allocated to Dom0, they can float between physical cores. VCPUs don’t really line up with cores, you can assign 8 vcpus on a DomU  on a 4 core Dom0 box for example. 8 cpus will appear in the VM but Xen will try to allocate the request within its 4 physucal cores. Generally assigning more VPUs than you have physical cores is pointless.

 

Q3: No SMP for a DOMU will mean the kernel is not SMP aware, this can save a small amount of overhead and improve scheduling in certain cases on a single core DOMU. I’m not sure what the affect would be on Dom0, my guess is it won’t be good.

 

 

 

Rob

 

From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of lei yang
Sent: 21 May 2010 04:09
To: Xen Mailing List; xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-users] What's the different for "dom0_max_vcpus=4dom0_vcpus_pin" and "dom0_max_vcpus=4" ?

 

Hi experts,


Q1:What's the different for "dom0_max_vcpus=4 dom0_vcpus_pin" and  "dom0_max_vcpus=4" ?
which will get better performance

Q2: dom0_max_vcpus=4 means "core0-3 will be just used by dom0" or means "4 cores(not dedicate cores) will be used by dom0, eg: core2-5 or core3-6?

Q3.what does mean "nosmp" , xen, dom0,domU, will just use one core????if so, can we specify the use different core. eg: dom0=core2 domU=core3? xen will use just one core?

Thanks
Lei








--
"We learn from failure, not from success!"

The SAQ Group

Registered Office: 18 Chapel Street, Petersfield, Hampshire GU32 3DZ
SAQ is the trading name of SEMTEC Limited. Registered in England & Wales
Company Number: 06481952

 

http://www.saqnet.co.uk AS29219

SAQ Group Delivers high quality, honestly priced communication and I.T. services to UK Business.

Broadband : Domains : Email : Hosting : CoLo : Servers : Racks : Transit : Backups : Managed Networks : Remote Support.

 

 SAQ Group

 

ISPA Member

_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-users