| Re: Performance Question [message #11044 is a reply to message #11040] |
Mon, 12 March 2007 13:13   |
dev
Messages: 1693
Registered: September 2005
Location: Moscow
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Senior Member |
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It would be great, since then we could try to reproduce.
| dietmar wrote on Mon, 12 March 2007 15:45 |
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- what environment do you refer to when refering to native? host system? Which OS/kernel etc.?
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debian/2.6.18-3
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- during the test you used most likely different directories for storing emails etc. The fact is that HDD speed varies very much for disk beginning and end.
So to make results comparable you should do the following:
a) create a separate partition of size which will be used totally up (plus some small reserve)
b) mount this partition to /var/spool when testing host environment and /vz/root/VEID/var/spool when testing VE.
This will guarantee that the same physical sectors of HDD will be used in both tests.
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Do you think that explains 15-20% Performance loss? Anyways, I cant change that for several reasons.
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It can account easily for almost double performance variations in some cases. Though I don't claim it is 100% the issue in your test case, just trying to provide more likely reasons for performance differences and which we can check for.
| dietmar wrote on Mon, 12 March 2007 15:45 |
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- set VE UBC setting to unlimited. This will prevent resource shortages during the test.
There can be other tunings done and checked for (e.g. mounting /vz with noatime), but w/o test case and test procedure it is hard to advise.
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I already set UBC settings to unlimited, but still get 15% less performance (which is quite good compared to other VM technologies)
| dietmar wrote on Mon, 12 March 2007 15:45 |
I'm pretty sure it can be optimized further out. It's just not that easy to find out the bottleneck remotely  maybe it's possible to get an access to your testbed?
Do you use 100Mb or 1Gb link?
I wonder if someone else did performance tests on comparable systems (mail server, mail gateways) running on OpenVZ?
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[Updated on: Mon, 12 March 2007 13:14] Report message to a moderator |
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