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Re: [Xen-users] Xen performance

To: anorton@xxxxxxx
Subject: Re: [Xen-users] Xen performance
From: Miguel Filipe <miguel.filipe@xxxxxxxxx>
Date: Mon, 17 Oct 2005 03:29:00 +0100
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On 10/11/05, Angela Norton <anorton@xxxxxxx> wrote:
Hi all,
While doing some benchmarking of Xen, I ran across a couple performance issues. I am wondering if anyone else has noticed this and whether there is anything I can do to tune the performance.

About your performance:
- You should use lvm volumes for your guest systems, that should give better I/O performance.
- Disable tls
- more IO performance: change FS, tune FS..


about the issues found, can't comment, but you could probably compare those results to vmware or qemu, to assert if the performance should be better.

Like the other reply says, hw is allways better than with some extra operating system layering and doing virtualization.
It would be more fair to compare performance between virtualization technologies.
Of course hw performance could be used has a baseline.
 

The setup:
CPU: Athlon XP 2500+ (1826.005 MHz)
RAM: Limited to 256 MB in native and xenU
Disk:Maxtor 6B200P0, ATA DISK drive
Motherboard: ASUS A7VBX-MX SE
Network: tested only loopback interface.

I have Fedora Core 4 installed as dom0, with Scientific Linux 3.0.7 (RHEL3) installed on a separate partition as the single domU. I installed the FC4 xen rpms (xen-3.0-0.20050912.fc4, kernel-xenU-2.6.12-1.1454_FC4, kernel-xen0-2.6.12-1.1454_FC4) using yum.

I used the following benchmark tools/suites:
bonnie++-1.03a
UnixBench 4.1.0
ab
lmbench 3.0-a5

The areas where I saw the greatest performance hit were in system calls, process creation, and pipe throughput. Here are some selected results:

UnixBench:
============

Scientific Linux 3 Native:
  BYTE UNIX Benchmarks (Version 4.1.0)
  System -- Linux localhost.localdomain 2.4.21-27.0.2.EL #1 Tue Jan 18 20:27:31 CST 2005 i686 athlon i386 GNU/
Linux
  Start Benchmark Run: Thu Sep 22 15:23:17 PDT 2005
   2 interactive users.
   15:23:17  up 12 min,  2 users,  load average: 0.03, 0.08, 0.05
  lrwxr-xr-x    1 root     root            4 Sep  9 10:56 /bin/sh -> bash
  /bin/sh: symbolic link to bash
  /dev/hdc11            20161172   5059592  14077440  27% /
<--snip-->
System Call Overhead                     995605.1 lps   (10.0 secs, 10 samples)
Pipe Throughput                          1135376.3 lps   (10.0 secs, 10 samples)
Pipe-based Context Switching             375521.7 lps   (10.0 secs, 10 samples)
Process Creation                           9476.4 lps   (30.0 secs, 3 samples)
Execl Throughput                           2918.3 lps   (29.7 secs, 3 samples)
<--snip-->
                     INDEX VALUES
TEST                                        BASELINE     RESULT      INDEX

Dhrystone 2 using register variables        116700.0  4307104.5      369.1
Double-Precision Whetstone                      55.0      980.4      178.3
Execl Throughput                                43.0     2918.3      678.7
File Copy 1024 bufsize 2000 maxblocks         3960.0   143780.0      363.1
File Copy 256 bufsize 500 maxblocks           1655.0    72156.0      436.0
File Copy 4096 bufsize 8000 maxblocks         5800.0   192427.0      331.8
Pipe Throughput                              12440.0  1135376.3      912.7
Process Creation                               126.0     9476.4      752.1
Shell Scripts (8 concurrent)                     6.0      329.7      549.5
System Call Overhead                         15000.0   995605.1      663.7
                                                                 =========
     FINAL SCORE                                                     475.2

--------------------------------------------

SL3 XenU
  BYTE UNIX Benchmarks (Version 4.1.0)
  System -- Linux localhost.localdomain 2.6.12-1.1454_FC4xenU #1 SMP Fri Sep 9 00:45:34 EDT 2005 i686 athlon i386 GNU/Linux
  Start Benchmark Run: Fri Sep 23 09:08:23 PDT 2005
   1 interactive users.
   09:08:23  up 0 min,  1 user,  load average: 0.95, 0.25, 0.08
  lrwxr-xr-x    1 root     root            4 Sep  9 10:56 /bin/sh -> bash
  /bin/sh: symbolic link to bash
  /dev/sda1             20161172   5058964  14078068  27% /
<--snip-->
System Call Overhead                     969225.3 lps   (10.0 secs, 10 samples)
Pipe Throughput                          619270.7 lps   (10.0 secs, 10 samples)
Pipe-based Context Switching              85183.9 lps   (10.0 secs, 10 samples)
Process Creation                           3014.6 lps   (30.0 secs, 3 samples)
Execl Throughput                           1807.4 lps   (29.9 secs, 3 samples)
<--snip-->
                     INDEX VALUES           
TEST                                        BASELINE     RESULT      INDEX

Dhrystone 2 using register variables        116700.0  4288647.9      367.5
Double-Precision Whetstone                      55.0      976.3      177.5
Execl Throughput                                43.0     1807.4      420.3
File Copy 1024 bufsize 2000 maxblocks         3960.0   143559.0      362.5
File Copy 256 bufsize 500 maxblocks           1655.0    70328.0      424.9
File Copy 4096 bufsize 8000 maxblocks         5800.0   186297.0      321.2
Pipe Throughput                              12440.0   619270.7      497.8
Process Creation                               126.0     3014.6      239.3
Shell Scripts (8 concurrent)                     6.0      188.0      313.3
System Call Overhead                         15000.0   969225.3      646.2
                                                                 =========
     FINAL SCORE                                                     356.0

---------------------------------------------------------------------------------

lmbench Selected Results:
==========================

SL3 Native:
<--snip-->
Simple syscall: 0.1516 microseconds
Simple read: 0.2147 microseconds
Simple write: 0.1817 microseconds
Simple stat: 1.8486 microseconds
Simple fstat: 0.3026 microseconds
Simple open/close: 2.2201 microseconds
<--snip-->
Protection fault: 0.2196 microseconds
Pipe latency: 2.2539 microseconds
AF_UNIX sock stream latency: 4.8221 microseconds
Process fork+exit: 143.7297 microseconds
Process fork+execve: 483.0833 microseconds
Process fork+/bin/sh -c: 1884.0000 microseconds

-------------------------------------------------

SL3 XenU:
<--snip-->
Simple syscall: 0.1671 microseconds
Simple read: 0.4090 microseconds
Simple write: 0.3588 microseconds
Simple stat: 3.5761 microseconds
Simple fstat: 0.5530 microseconds
Simple open/close: 3.9425 microseconds
<--snip-->
Protection fault: 0.5993 microseconds
Pipe latency: 12.1886 microseconds
AF_UNIX sock stream latency: 22.3485 microseconds
Process fork+exit: 365.8667 microseconds
Process fork+execve: 1066.4000 microseconds
Process fork+/bin/sh -c: 3826.0000 microseconds
<--snip-->

-------------------------------------------------------------------------



I can post the full results of these tests if anyone is interested.

Does anyone have any ideas for tuning the performance of the domUs? Are there any configurations that perform better than others?

Thank You,
Angela Norton

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--
Miguel Sousa Filipe
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