Re: Dom0 starvs DomU

[tg%gmplib.org@localhost (Torbjörn Granlund)]

Greg Troxel <gdt%ir.bbn.com@localhost> writes:

  I suspect that if you used a separate disk in the dom0 for the domU
  storage, you wouldn't have this issue, but that's avoiding the issue.  I
  also wonder if raw partitions/LVM would be better.
  
This was easy for me to test.  I have an E5-1650 v2 with 3 disks.
One is owned my FreeBSD 9.3.

I now tried "cd /usr/pkgsrc/sysutils/xentoold4 ; make update' in Dom0
while trying an ls Mail/inbox in the Domu.  It has not output a single
file after 5 minutes.

By C-Z'ing the build, it outputs files within a second.

The system has three disks:

disk:	SATA SSD 2.5" 240GB Samsung SM843Tn (wd0)
disk:	SATA SSD 2.5" 480GB Samsung SV843T  (wd1)
disk:	SATA SSD 2.5" 480GB Samsung SV843T  (wd2)

NetBSD Dom0 is installed on wd0.
The middle disk is given to FreeBSD like this:

disk = ['phy:/dev/wd1d,hda,w']

  It is probably not super hard to read the xen code in the dom0 kernel
  to see what's going on, and there may be performance counters you can
  look at.
  
Oh well, I hope some NetBSD hacker improves the situation.  :-)

I have moved a few of the systems off NetBSD Dom0 as an intermediate
solution.  I'll move back to NetBSD if it works for me again.  I mention
this because it is worth noticing that bogging down a Linux/Xen system
system seems much harder.  (These systems use Xen 4.4.)

-- 
Torbjörn
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