RE: [Xen-ia64-devel] HVM Multi-Processor Performance followup

["Xu, Anthony" <anthony.xu@xxxxxxxxx>]

Thanks for your efforts

 

You can see the drop in performance starts to get really bad at about 9 CPUs and beyond

 

If you increase guest vCPU number, the bottleneck may be dom0 vCPU number( only 1vCPU for dom0).

 

You can try configure two/four vCPU for dom0, the performance may be back.

 

a curious question,

 

Alex said there are ~70% degradation on RE-AIM7,

Your test result seems much better than his.

 

What's the difference of your test environment?

 

Thanks,

Anthony

 

---

From: xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Kayvan Sylvan
Sent: 2008年2月1日 8:57
To: xen-ia64-devel
Subject: [Xen-ia64-devel] HVM Multi-Processor Performance followup

Hi everyone,

 

A follow-up on the multiprocessor performance benchmark on HVM guests.

 

We ran the RE-AIM7 benchmarks on a 5-cell (40 CPU) machine and a single-cell 8-cpu NEC machine.

 

Here are the jobs per minute maximums.

 

You can see the drop in performance starts to get really bad at about 9 CPUs and beyond.

 

Questions:

 

1.       What can I do to help improve this situation?

2.       Are there any other experiments I can run?

3.       What tools/profilers will help to gather more data here?

 

I am very interested in helping to solve this problem! Thanks for your ideas and suggestions.

 

Best regards,

 

---Kayvan

 

 

	Xen performance comparison on 5-Cell NEC machine (each cell with 4 dual-core Itaniums)
	CPUs		Native Jobs/Min	HVM Jobs/Min			Overhead
	1		2037	1791			12.08%
	2		4076	3615			11.31%
	3		6090	5221			14.27%
	4		8118	6839			15.76%
	5		10119	8404			16.95%
	6		12037	9949			17.35%
	7		14106	11095			21.35%
	8		15953	12360			22.52%
	9		18059	13201			26.90%
	10		20170	13742			31.87%
	11		21896	13694			37.46%
	12		24079	13331			44.64%
	13		25992	12374			52.39%
	14		28072	11684			58.38%
	15		29931	11032			63.14%
	16		31696	10451			67.03%
	The guest OS was CentOS-4.6 with 2GB of memory,
	running under a Dom0 that was limited to 1 VCPU.
	Xen performance comparison on 1-Cell NEC machine (4 dual core Itanium Montecito)
	CPUs	Native Jobs/Min			HVM Jobs/Min	Overhead
	1	2037			1779	12.67%
	2	4067			3619	11.02%
	3	6097			5344	12.35%
	4	8112			7004	13.66%
	5	10145			8663	14.61%
	6	12023			10213	15.05%
	7	14083			11249	20.12%
	8	16182			12969	19.86%
	The guest OS was CentOS-4.6 with 2GB of memory,
	running under a Dom0 that was limited to 1 VCPU.

---

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Source: CPU Performance

 

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