freebsd stable - Feb 2017 - Problem with FreeBSD as a XenServer Guest - how to debug?

Hi,

I?ve opened a PR on this:

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=212681

and asked on freebsd-virtualization. But nothing came out of it.

Basically, I/O is very slow inside the FreeBSD guest. Linux guests are OK.
FreeBSD 10 or 11 doesn?t make a difference.
Haven?t been able to try 12.


How can one debug this?




Rainer

Hi Rainer,

isn't Amazon AWS xen-based?
I know Colin Percival (cperciva@) is running 
tarsnap.com on AWS, maybe he knows how 
to tune it properly?
Looks like he's the one providing FreeBSD 
images for AWS, too: https://aws.amazon.com/marketplace/pp/B01LWSWRED/
Amazon is probably running a heavily patched
version of Xen but looking at the images' 
sysctls & stuff and running one on your Xen-
Server might provide some insights - or at
least datapoints.

And then there's DTrace to dive into the 
kernel's inner workings*?

Oh, does Xen still provide emulation for other
storage controllers like SATA or SAS? If so
you may get an at least bearable performance
using those.

Regards, Florian

Am 4. Februar 2017 01:12:11 MEZ schrieb Rainer Duffner <rainer at
ultra-secure.de>:
> Hi,
> 
> I?ve opened a PR on this:
> 
> https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=212681
> 
> and asked on freebsd-virtualization. But nothing came out of it.
> 
> Basically, I/O is very slow inside the FreeBSD guest. Linux guests are
> OK.
> FreeBSD 10 or 11 doesn?t make a difference.
> Haven?t been able to try 12.
> 
> 
> How can one debug this?
> 
> 
> 
> 
> Rainer
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