Re: [Xen-users] Xen Performance

Peter Booth
Sat, 30 May 2009 20:11:23 -0000

In this example, swapping/page scanning was not an issue.

On May 30, 2009, at 4:05 PM, Luke S Crawford wrote:

> Peter Booth <peter_booth@mac.com> writes:
>> One real world example:
>> native Linux:  		page response times of (  400ms/150ms)
>> [mean/standard  deviation]
>> Xen VM:			page response times of (  700ms/3.5s)
>> [mean/standard  deviation]
>>
>> In this scenario, we have mean response times that are almost 100%
>> worse, and the 90th percentile is 1000% worse.
>
> Yeah, but if your average native times are 400ms, you are very likely
> already hitting swap and experiencing what I would call unacceptable
> performance.  It''s no suprise that swap on a shared device is
going
> to be
> slower than a non-shared swap.
>
> Hm.  unless that xen vm is on a xen box doing nothing else, in which
> case
> the results whould suprise me quite a lot (unless you were using HVM
> mode
> or had less ram in the xen vm than in the native box)