Re: KVM usability

From: Anthony Liguori <anthony@codemonkey.ws>
To: Alexander Graf <agraf@suse.de>
Cc: kirkland@canonical.com, Avi Kivity <avi@redhat.com>,
	Ingo Molnar <mingo@elte.hu>,
	"Zhang, Yanmin" <yanmin_zhang@linux.intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	ming.m.lin@intel.com, sheng.yang@intel.com,
	Jes Sorensen <Jes.Sorensen@redhat.com>,
	KVM General <kvm@vger.kernel.org>,
	Zachary Amsden <zamsden@redhat.com>,
	Gleb Natapov <gleb@redhat.com>,
	Arnaldo Carvalho de Melo <acme@redhat.com>,
	Fr??d??ric Weisbecker <fweisbec@gmail.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Arjan van de Ven <arjan@infradead.org>
Subject: Re: KVM usability
Date: Tue, 09 Mar 2010 08:50:21 -0600	[thread overview]
Message-ID: <4B96602D.8050604@codemonkey.ws> (raw)
In-Reply-To: <6CF4AA9A-5C83-42C2-80BF-AEEFE68A99B6@suse.de>

On 03/09/2010 08:38 AM, Alexander Graf wrote:
> On 09.03.2010, at 15:32, Dustin Kirkland wrote:
>
>    
>> On Tue, 2010-03-09 at 15:32 +0200, Avi Kivity wrote:
>>      
>>> On 03/02/2010 04:36 AM, Anthony Liguori wrote:
>>>        
>>>>> I keep a patch in the SUSE version for quite some time now that bumps
>>>>> the default to 384 for qemu-kvm. That was the first "round" number
>>>>> where an openSUSE installation worked.
>>>>>            
>>>> If someone works up a patch and tests at least a couple types of
>>>> guests to confirm that they all install with that number, I'd be happy
>>>> to apply it (although we need some trickery to support older pc
>>>> versions).
>>>>          
>>> We should avoid changing defaults.  I don't think in this case it
>>> matters, since everyone specifies -m anyway, but as a general rule
>>> changing defaults = breakage for the unwary.  At least make the default
>>> part of the machine type to preserve compatibility.
>>>        
>> In that case, Alex, where can I find your +384M patch, because I'd like
>> to carry the same one in Ubuntu...
>>      
> It's all in the openSUSE build service. The direct access URL (login required FWIW) is here:
>
> https://build.opensuse.org/package/view_file?file=kvm-qemu-default-memsize.patch&package=kvm&project=Virtualization
>
> It merely changes DEFAULT_RAM_SIZE in vl.c from 128 to 384 for the "kvm" package.
>    

We should attempt to do three things with default ram size:

1) bump it up to a more reasonable number
2) make it specified in the global default config
3) make sure we can provide compatibility support for older machine types

> Alex
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