Dirk Estreng
2006-Jan-03 14:09 UTC
[Xen-users] xen 2.0.7 on SuSE 9.3 very slow responses in dom0
Hi there,
I downgraded my machine from xen3 to xen 2.0.7 on suse93 due to several problems
with xen3/suse 10.0
Now I experience massive performance degradation in dom0 while installing domUs.
It seems like "some" network OR disk IO is just slowing down dom0.
There aren´t
yet any domUs running I just install them in LVM lv´s.
Running on an AMD Sempron 2600
2 GB RAM
80 GB ATA harddisk with UDMA on
Using suse 9.3 with xen 2.0.7 from Kurt Garloff
DomU on LVM
It seems to me like the machine totally looses interactive response while
copying or transfering files. Where to start looking? Is it a xen/dom0 problem
or is it due to hardware problems? Or is it something like a
"sheduler" limiting
dom0 performance?
How to find the bottleneck? I tried sysstat but don´t know how to interpret the
values...
-------------------------
Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
hda 20.60 6.40 2227.20 32 11136
hdc 0.00 0.00 0.00 0 0
avg-cpu: %user %nice %sys %iowait %idle
68.80 0.00 19.80 11.40 0.00
Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
hda 38.00 49.60 4137.60 248 20688
hdc 0.00 0.00 0.00 0 0
avg-cpu: %user %nice %sys %iowait %idle
55.40 0.00 20.60 24.00 0.00
Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
hda 23.20 62.40 8096.00 312 40480
hdc 0.00 0.00 0.00 0 0
avg-cpu: %user %nice %sys %iowait %idle
4.00 0.00 6.00 90.00 0.00
Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
hda 38.80 6.40 803.20 32 4016
hdc 0.00 0.00 0.00 0 0
avg-cpu: %user %nice %sys %iowait %idle
30.60 0.00 21.40 48.00 0.00
Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
hda 63.40 604.80 1217.60 3024 6088
hdc 0.00 0.00 0.00 0 0
-------------------------
Thanks
Dirk
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Dirk Estreng
2006-Jan-03 14:56 UTC
[Xen-users] Re: xen 2.0.7 on SuSE 9.3 very slow responses in dom0
Tracked it down a little more: running: "bonnie++ -s 2048 -d /var/tmp -u root" in dom0 watching: "iostat -x -d 2" gives: await svctm %util 6953.33 111.11 100.00 9039.17 166.67 100.00 (...) man iostat says: "%util: Percentage of CPU time during which I/O requests were issued to the device (bandwidth utilization for the device). Device saturation occurs when this value is close to 100%. Running: "mpstat 3 5" while bonnie++ runs shows: 15:51:33 CPU %user %nice %system %iowait 15:51:36 all 0.00 0.00 0.00 99.67 15:51:39 all 0.00 0.00 0.00 100.00 15:51:42 all 20.33 0.00 14.00 65.67 15:51:45 all 0.00 0.00 0.00 100.00 15:51:48 all 0.00 0.00 0.00 100.00 man mpstat says: "%iowait: Show the percentage of time that the CPU or CPUs were idle during which the system had an outstanding disk I/O request." So as far as i understand my ATA drive locks up my CPU... Where is the problem?? I am running: xen2.0.7 on suse 9.3 with 2.6.11.4-21.8-xen Thanks Dirk _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Joost Roeleveld
2006-Jan-04 13:56 UTC
Re: [Xen-users] Re: xen 2.0.7 on SuSE 9.3 very slow responses in dom0
On Jan 03, 2006 02:56 PM, Dirk Estreng <dirk.estreng@gmx.de> wrote:>Tracked it down a little more: ><snipped analysis>> >So as far as i understand my ATA drive locks up my CPU... >Where is the problem?? > >I am running: >xen2.0.7 on suse 9.3 with 2.6.11.4-21.8-xenHi Dirk, I''m not yet familiar with Xen, subscribed to the list to get some pointers while waiting for the new computer to arrive. I have seen a similar problem with a ''normal'' linux install though. Do you have DMA enabled? Use hdparm to check this, not sure which flags to use, can''t check at the moment. Without DMA, the performance of harddrives are really bad and can cause very high CPU utilisation. If you can''t enable DMA (using hdparm), you will need to load the correct IDE-driver for your system, lspci should be able to tell you which chipset you are using and then you need to configure the correct IDE driver into the kernel. You might need to disable the generic driver to avoid it claiming the device before the proper driver gets to it. Hope this helps. Kind regards, Joost _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Dirk Estreng
2006-Jan-05 07:52 UTC
[Xen-users] Re: xen 2.0.7 on SuSE 9.3 very slow responses in dom0
Joost Roeleveld <joost <at> roeleveld.co.uk> writes:> > On Jan 03, 2006 02:56 PM, Dirk Estreng <dirk.estreng <at> gmx.de> wrote: > > >Tracked it down a little more: > > > > <snipped analysis> > > > > >So as far as i understand my ATA drive locks up my CPU... > >Where is the problem?? > > > >I am running: > >xen2.0.7 on suse 9.3 with 2.6.11.4-21.8-xen > > Hi Dirk, > > I''m not yet familiar with Xen, subscribed to the list to get some > pointers while waiting for the new computer to arrive. > I have seen a similar problem with a ''normal'' linux install though. > Do you have DMA enabled? > Use hdparm to check this, not sure which flags to use, can''t check at > the moment. > > Without DMA, the performance of harddrives are really bad and can cause > very high CPU utilisation. > > If you can''t enable DMA (using hdparm), you will need to load the > correct IDE-driver for your system, lspci should be able to tell you > which chipset you are using and then you need to configure the correct > IDE driver into the kernel. > You might need to disable the generic driver to avoid it claiming the > device before the proper driver gets to it. > > Hope this helps. > > Kind regards, > > Joost >Hi Joost, thanks for your reply and help! I think it was indeed a problem with the chipset of my test machine (SiS). The onboard IDE controller seems not to work correctly (in DMA mode) with my XEN kernel. I completely overlooked this fact because without XEN it was running fast and afaik hdparm said the drive was using UDMA (in fact this was one of the first things that came up my mind)... BUT it seems the drive WAS running in slow PIO mode. Now it works ;-) thanks dirk _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users