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RE: [Xen-devel] [PATCH] Fix auto-ballooning of dom0 for HVM domains

To: "Charles Coffing" <ccoffing@xxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-devel] [PATCH] Fix auto-ballooning of dom0 for HVM domains
From: "Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx>
Date: Fri, 19 May 2006 12:23:59 +0800
Delivery-date: Thu, 18 May 2006 21:24:31 -0700
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Thread-topic: [Xen-devel] [PATCH] Fix auto-ballooning of dom0 for HVM domains
Hi, Charles
        Just one suggestion, for  xen-hvm-auto-balloon.diff, how about
             xc.domain_setmaxmem(self.domid, m)
             xc.domain_setmaxmem(self.domid, self.info['memory'] * 1024)

The maxmem would be used to check when guest try to increase memory.

Also, does anyone know the what the BALLOON_OUT_SLACK on
tools/python/xen/xend/balloon.py stands for? The comments said it is
"physinfo details are rounded".

Yunhong Jiang

 >-----Original Message-----
>From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx 
>[mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of 
>Charles Coffing
>Sent: Friday, May 19, 2006 1:04 AM
>To: xen-devel@xxxxxxxxxxxxxxxxxxx
>Subject: [Xen-devel] [PATCH] Fix auto-ballooning of dom0 for 
>HVM domains
>I've been trying to make the auto-ballooning of domain 0 work reliably
>for HVM domains.
>Patch #1 is a simple bug fix, in preparation for patch #2.  Patch #2
>tries to calculate how much memory is needed for HVM domains (XenSource
>bug #521) and is certainly open for discussion.  Patches apply cleanly
>to both 3.0-testing and unstable.
>Patch #1 (xen-hvm-auto-balloon.diff):
>When a domain (whether para- or fully-virtualized) reports how much
>overhead memory it requires (via getDomainMemory in image.py), all such
>memory was immediately allocated to the domain itself.  This is
>certainly incorrect for HVM domains, since additional
>increase_reservation calls are made later in qemu.  Since all ballooned
>memory is already taken, qemu will fail.  The fix is to treat the
>requested memory size and the overhead size as separate values.  The
>requested memory size is immediately allocated to the new domain; the
>overhead is left unallocated for whatever else might need it later.
>Patch #2 (xen-get-dom-memory.diff):
>This patch calculates the overhead needed for HVM domains.  If HVM is
>supported by the hardware, I add a little ballooning overhead to
>paravirtualized VMs also, to avoid low-memory situations.  (There are
>various unchecked alloc_domheap_pages calls in shadow*.c that I am
>trying to avoid tripping over for now...)  The values in this 
>patch work
>fine on 32 bit; I may update them later based on feedback 
>and/or testing
>on 64 bit.

Attachment: xen-hvm-auto-balloon.diff
Description: xen-hvm-auto-balloon.diff

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