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OpenVZ Kernel generally slow? [message #35151] Thu, 05 March 2009 14:13 Go to next message
disaster is currently offline  disaster
Messages: 158
Registered: February 2006
Senior Member
Hi!

Is OpenVZ Kernel slow?

When i'm running unixbench-4.1.0-wht-2 on the Host Machine with a non OpenVZ 2.6.27.18 Vanilla Kernel i get the following results:

                     INDEX VALUES            
TEST                                        BASELINE     RESULT      INDEX

Dhrystone 2 using register variables        376783.7 50530575.6     1341.1
Double-Precision Whetstone                      83.1     1674.4      201.5
Execl Throughput                               188.3    25659.0     1362.7
File Copy 1024 bufsize 2000 maxblocks         2672.0   615188.0     2302.4
File Copy 256 bufsize 500 maxblocks           1077.0   196511.0     1824.6
File Read 4096 bufsize 8000 maxblocks        15382.0  1422019.0      924.5
Pipe Throughput                             111814.6 11214912.1     1003.0
Pipe-based Context Switching                 15448.6  2299837.1     1488.7
Process Creation                               569.3    64781.5     1137.9
Shell Scripts (8 concurrent)                    44.8     4974.5     1110.4
System Call Overhead                        114433.5 17398060.3     1520.4
                                                                 =========
     FINAL SCORE                                                    1136.9


When i install OpenVZ 2.6.18 or 2.6.26 Kernel and run WHT i get something like this:
                     INDEX VALUES            
TEST                                        BASELINE     RESULT      INDEX

Dhrystone 2 using register variables        376783.7 43674178.6     1159.1
Double-Precision Whetstone                      83.1     1467.1      176.5
Execl Throughput                               188.3     5866.4      311.5
File Copy 1024 bufsize 2000 maxblocks         2672.0   398961.0     1493.1
File Copy 256 bufsize 500 maxblocks           1077.0   207161.0     1923.5
File Read 4096 bufsize 8000 maxblocks        15382.0  1213218.0      788.7
Pipe Throughput                             111814.6 10492852.7      938.4
Pipe-based Context Switching                 15448.6  2225406.2     1440.5
Process Creation                               569.3    13309.5      233.8
Shell Scripts (8 concurrent)                    44.8     1571.6      350.8
System Call Overhead                        114433.5 13993448.6     1222.8
                                                                 =========
     FINAL SCORE                                                     699.4


Stefan

[Updated on: Thu, 05 March 2009 14:14]

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Re: OpenVZ Kernel generally slow? [message #35159 is a reply to message #35151] Fri, 06 March 2009 11:14 Go to previous messageGo to next message
maratrus is currently offline  maratrus
Messages: 1495
Registered: August 2007
Location: Moscow
Senior Member
Hello,

could you possibly try
OpenVZ 2.6.27 kernel
http://download.openvz.org/kernel/branches/2.6.27/2.6.27-aiv azovsky.1/

and also 2.6.18 pure RHEL5 kernel

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Re: OpenVZ Kernel generally slow? [message #35160 is a reply to message #35151] Fri, 06 March 2009 12:28 Go to previous messageGo to next message
disaster is currently offline  disaster
Messages: 158
Registered: February 2006
Senior Member
Hi!

I cannot test plain RHEL 5 Kernel cause i use Debian instead of Redhat.

Here are the Results from OpenVZ 2.6.27:
                     INDEX VALUES            
TEST                                        BASELINE     RESULT      INDEX

Dhrystone 2 using register variables        376783.7 44178754.0     1172.5
Double-Precision Whetstone                      83.1     1458.9      175.6
Execl Throughput                               188.3     4718.0      250.6
File Copy 1024 bufsize 2000 maxblocks         2672.0   569144.0     2130.0
File Copy 256 bufsize 500 maxblocks           1077.0   178028.0     1653.0
File Read 4096 bufsize 8000 maxblocks        15382.0  1172482.0      762.2
Pipe Throughput                             111814.6  9205265.5      823.3
Pipe-based Context Switching                 15448.6  1949721.8     1262.1
Process Creation                               569.3    10826.7      190.2
Shell Scripts (8 concurrent)                    44.8     1274.3      284.4
System Call Overhead                        114433.5 13813705.2     1207.1
                                                                 =========
     FINAL SCORE                                                     654.2


I'm using the provided default configs (only change processor Type to Intel Xeon).

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Re: OpenVZ Kernel generally slow? [message #35161 is a reply to message #35160] Fri, 06 March 2009 12:33 Go to previous messageGo to next message
maratrus is currently offline  maratrus
Messages: 1495
Registered: August 2007
Location: Moscow
Senior Member
Hello,

could you please specify your environment in detail.
As far as I understand this test is running on the HN. Am I right?

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Re: OpenVZ Kernel generally slow? [message #35171 is a reply to message #35151] Fri, 06 March 2009 17:17 Go to previous messageGo to next message
disaster is currently offline  disaster
Messages: 158
Registered: February 2006
Senior Member
You're right - it is running in the HN. It is a plain Debian 4.0. No VPS installed at the moment. Only installed OpenVZ Kernel instead of the vanilla one.

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Re: OpenVZ Kernel generally slow? [message #35189 is a reply to message #35151] Mon, 09 March 2009 09:18 Go to previous messageGo to next message
disaster is currently offline  disaster
Messages: 158
Registered: February 2006
Senior Member
If you need more information - please ask.

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Re: OpenVZ Kernel generally slow? [message #35217 is a reply to message #35189] Tue, 10 March 2009 09:00 Go to previous messageGo to next message
maratrus is currently offline  maratrus
Messages: 1495
Registered: August 2007
Location: Moscow
Senior Member
Hello,

could you please check what kind of i/o schedulers are used
when vanilla kernel is booted and when OpenVZ is booted?
It may be obtained via "cat /sys/block/sdb/queue/scheduler".
The same interface can be used while changing that value.

"echo "SOMETHING" > /sys/block/sdb/queue/scheduler".

And some additional information (just in case):
from both kernels

- cat /proc/meminfo
- cat /proc/mounts
- tune2fs -l $DEVICE

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Re: OpenVZ Kernel generally slow? [message #35219 is a reply to message #35217] Tue, 10 March 2009 09:07 Go to previous messageGo to next message
maratrus is currently offline  maratrus
Messages: 1495
Registered: August 2007
Location: Moscow
Senior Member
I've told about i/o schedulers but forgotten to ask you experiment with different schedulers.
Thank you.

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Re: OpenVZ Kernel generally slow? [message #35224 is a reply to message #35151] Tue, 10 March 2009 09:49 Go to previous messageGo to next message
disaster is currently offline  disaster
Messages: 158
Registered: February 2006
Senior Member
Both are CFQ and i've also tried Anticipatory sched no difference. I'll now setup another machine - cause i needed the last one and will post results again with the additional informations you want.

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Re: OpenVZ Kernel generally slow? [message #35225 is a reply to message #35224] Tue, 10 March 2009 10:07 Go to previous messageGo to next message
maratrus is currently offline  maratrus
Messages: 1495
Registered: August 2007
Location: Moscow
Senior Member
Hi,

seems my previous suggestions were not quite correct.

Tests that are "failed" on OpenVZ kernel are: "Execl Throughput" and "Process Creation".
An overhead during the process creation is normal because OpenVZ accounts memory. But the suspicious fact is SUCH big overhead!

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Re: OpenVZ Kernel generally slow? [message #35226 is a reply to message #35151] Tue, 10 March 2009 10:16 Go to previous messageGo to next message
disaster is currently offline  disaster
Messages: 158
Registered: February 2006
Senior Member
Yeah that's right - i was wonderung why you wanted so much information about the filesystem and harddisks Smile I've seen that the process results are really bad and i also know that OpenVZ has a overhead. But so much?? Any idea?

[Updated on: Tue, 10 March 2009 10:17]

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Re: OpenVZ Kernel generally slow? [message #35227 is a reply to message #35226] Tue, 10 March 2009 10:49 Go to previous messageGo to next message
maratrus is currently offline  maratrus
Messages: 1495
Registered: August 2007
Location: Moscow
Senior Member
I cannot investigate this issue closely right now.
I think it's important not to lose your efforts and results.
So, what do you think about filing a bug?
http://bugzilla.openvz.org/

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Re: OpenVZ Kernel generally slow? [message #35228 is a reply to message #35151] Tue, 10 March 2009 10:59 Go to previous message
disaster is currently offline  disaster
Messages: 158
Registered: February 2006
Senior Member
i've made a bug report:
http://bugzilla.openvz.org/show_bug.cgi?id=1210

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