Re: 50% slowdown on 2 processor XEN 4.1.3 vs 1 processor system

[Harry Waddell <waddell%caravaninfotech.com@localhost>]

Just a quick followup. It seems that although netbsd-GENERIC could
control the cpu clock just fine, netbsd-XEN3_DOM0 defers this to the xen kernel,
which could not. There was also a bug in the MB bios, which would not let me
disable EIST -- essentially, it always ran at the lowest, rather than the
highest speed. I tried every motherboard and xen boot option I could think of,
messed with xenpm, and nothing seemed to help.

So, I convinced my supplier to let me swap it for something that I know
works correctly, which wasn't hard as he seemed to feel that it was
going to be very hard to get supermicro to fix this issue. So, if you
plan to run netbsd and xen, avoid the supermicro X9DR3-F with AMI
2.14.x bios. If your case will hold an EE-ATX board, the supermicro
X9DRi-LN4+ with AMI with 2.15.x bios seems to work as it should. 

Thanks to all who helped look into this. 

Harry Waddell





 

On Mon, 26 Nov 2012 23:06:37 -0800
Harry Waddell <waddell%caravaninfotech.com@localhost> wrote:

> On Tue, 27 Nov 2012 00:09:32 -0600
> "Cherry G. Mathew" <cherry.g.mathew%gmail.com@localhost> wrote:
> 
> > On 26 November 2012 03:00, Harry Waddell 
> > <waddell%caravaninfotech.com@localhost> wrote:
> > >
> > > I just built a new server with 2 x E5-2630 processors and was comparing 
> > > the
> > > performance to a nearly identical xen server with 1 x E5-1660 processor 
> > > and
> > > found that on a per core basis, instead of being about 50% faster ( as 
> > > one would expect from the clock speed given that the architecture is 
> > > nearly identical ), the E5-1660 system is %300 faster, so I ran some 
> > > benchmarks and started looking for a pattern.
> > >
> > > Both systems run NetBSD amd64 6.0-STABLE with xen 4.1.3. The 2
> > > processor system is running only 1/2 as fast with the XEN3_DOM0 kernel
> > 
> > I hope you realise that NetBSD dom0 is not MP capable ?
> > 
> > -- 
> > ~Cherry
> > 
> 
> Not only do I know that, but I believe your name is next to that goal on the 
> xen roadmap. ;-) I did however setup a 24 vcpu domU just to see if it worked, 
> and I'm glad to say it did. 
> 
> Anyway, yes, all the performance measures I gathered were single threaded. 
> "top" showed that only one cpu core was engaged. The followup email I sent 
> earlier today with some sysbench results show that I'm only running single 
> threaded tests. 
> 
> Please let me know if you think of any info I can supply or any tests I can 
> run. 
> 
> HW
> 
>  
> 
>