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[Xen-devel] query on pinning mechanism

To: <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: [Xen-devel] query on pinning mechanism
From: "Pradeep Singh, TLS-Chennai" <pradeep_s@xxxxxx>
Date: Tue, 13 Mar 2007 11:02:11 +0530
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Thread-topic: query on pinning mechanism

hi all,
After going through the code, this is what i make out of pinning in Xen.
Please correct me if i am wrong.

A page can have mutually exclusive roles in the Xen depending on its current use.
A page can have its reference count incremented or type count incremented depending on its usage to avoid returning it to the pool of free pages and to change its page type.

At times guest wants some of its page tables to exist even after a preemption.So that page tables exist it must not loose its reference count.Pinning makes sure that the page has a usage of 1 atleast for that particular page and avoids that page to be assigned to free pool or reclaimed for a different type. 

Am i right?

Another doubt, Xen guest domains cannot swap pseduo physical memory.Am i right?

Can xen lxr repository on xensource be changed to a more organised way wrt versions ?
linux-2.6.xx-xen etc are there but xen directory is same for all of them.

Can the directories be made version wise with all included sources as they appear on untarring?

Thank you.

--pradeep
-----------------------
Pradeep Singh
Member Technical Staff
Core Technology Divison
53, Greams Road.
HCL Technologies, Chennai

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