Ian,
(Sorry. I sent things from the wrong e-mail address, so you've probably
been getting bounces. This one should work.)
My config is attached,
Both dom0 and the domU are SLES 10, so I don't know why the "idle"
performance of the two should be different. The obvious asymmetry is the
disk. Since the disk isn't direct, any disk I/O by the domU would
certainly impact dom0, but I don't think there should be much, if any. I
did run a dom0 test with the domU started, but idle and there was no
real change to dom0's numbers.
What's the best way to gather information about what is going on with
the domains without perturbing them? (Or, at least, perturbing everyone
equally.)
As to the test, I am running netperf 2.4.1 on an outside machine to the
dom0 and the domU. (So the doms are running the netserver portion.) I
was originally running it in the doms to the outside machine, but when
the bad numbers showed up I moved it to the outside machine because I
wondered if the bad numbers were due to something happening to the
system time in domU. The numbers is the "outside" test to domU look worse.
Thanks,
John Byrne
Ian Pratt wrote:
There have been a couple of network receive throughput
performance regressions to domUs over time that were
subsequently fixed. I think one may have crept in to 3.0.3.
The report was (I believe) with a NIC directly assigned to the domU, so
not using netfront/back at all.
John: please can you give more details on your config.
Ian
Are you seeing any dropped packets on the vif associated with
your domU in your dom0? If so, propagating changeset
11861 from unstable may help:
changeset: 11861:637eace6d5c6
user: kfraser@xxxxxxxxxxxxxxxxxxxxx
date: Mon Oct 23 11:20:37 2006 +0100
summary: [NET] back: Fix packet queuing so that packets
are drained if the
In the past, we also had receive throughput issues to domUs
that were due to socket buffer size logic but those were
fixed a while ago.
Can you send netstat -i output from dom0?
Emmanuel.
On Mon, Nov 06, 2006 at 09:55:17PM -0800, John Byrne wrote:
I was asked to test direct I/O to a PV domU. Since, I had a system
with two NICs, I gave one to a domU and one dom0. (Each is
running the
same
kernel: xen 3.0.3 x86_64.)
I'm running netperf from an outside system to the domU and
dom0 and I
am seeing 30% less throughput for the domU vs dom0.
Is this to be expected? If so, why? If not, does anyone
have a guess
as to what I might be doing wrong or what the issue might be?
Thanks,
John Byrne
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disk = [ 'file:/disk2/vm1/hda,hda,w' ]
memory = 3072
vcpus = 1
builder = 'linux'
name = 'vm1'
#vif = [ 'mac=00:16:3e:55:0a:86' ]
localtime = 0
on_poweroff = 'destroy'
on_reboot = 'restart'
on_crash = 'restart'
extra = ' TERM=xterm'
#bootloader = '/usr/lib/xen/boot/domUloader.py'
#bootentry = 'hda2:/boot/vmlinuz-xen,/boot/initrd-xen'
kernel = '/disk2/vm1/vmlinuz-xen'
ramdisk = '/disk2/vm1/initrd-xen'
root = '/dev/hda2'
pci = [ '05:00.0' ]
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