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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-users] Disk-I/O Performance DomU vs Dom0
Hi,
I experience massive I/O performance-difference between Dom0 and DomU. To
simply show the impact, I use a logical volume striped over 6 hard-drives. Then
(write/read) enough bytes linear via dd zeros (on/from) this lv and compare the
time.
The result: inside DomU I get only about 30% of the I/O performance of the Dom0.
So, where is the handbrake, and how do I release it? Normaly there shouldbe no
such big difference. If you need more information about setup and config, to
give me a hint where else to search for my missing 70% performance, simply
reply inside the list.
Here are the gory details so far:
Preparations
==================================================================================================
Dom0: akaar
DomU: guinan
Create LV:
lvcreate --name=performance-test --size=20G --stripes=6 vg0
Attach LV to domU:
root@akaar:~# xm block-attach guinan phy:/dev/vg0/performance-test xvdc1 w
Test:
=====================================================================================================
============== Write
=== Dom0
root@akaar:~# date ; dd if=/dev/zero of=/dev/vg0/performance-test bs=1M
count=4000 ; sync ; date
Do 5. Apr 20:15:50 CEST 2012
4000+0 records in
4000+0 records out
4194304000 bytes (4,2 GB) copied, 7,34972 s, 571 MB/s
Do 5. Apr 20:15:58 CEST 2012
=== DomU
root@guinan:~# date ; dd if=/dev/zero of=/dev/xvdc1 bs=1M count=4000 ; sync ;
date
Do 5. Apr 20:34:50 CEST 2012
4000+0 records in
4000+0 records out
4194304000 bytes (4,2 GB) copied, 23,5331 s, 178 MB/s
Do 5. Apr 20:35:13 CEST 2012
============== Read
=== Dom0
root@akaar:~# date ; dd if=/dev/vg0/performance-test of=/dev/null bs=1M
count=4000 ; sync ; date
Do 5. Apr 20:21:38 CEST 2012
4000+0 records in
4000+0 records out
4194304000 bytes (4,2 GB) copied, 8,98257 s, 467 MB/s
Do 5. Apr 20:21:48 CEST 2012
=== DomU
root@guinan:~# date ; dd if=/dev/xvdc1 of=/dev/null bs=1M count=4000 ; sync ;
date
Do 5. Apr 20:38:04 CEST 2012
4000+0 records in
4000+0 records out
4194304000 bytes (4,2 GB) copied, 17,8235 s, 235 MB/s
Do 5. Apr 20:38:22 CEST 2012
==================================================================================================
==================================================================================================
==================================================================================================
Technical Data:
===================================================================================================
Hardware Poweredge 510 / 96GB RAM / 2x X5650
Storage 6 Nearline SAS Harddrives attached to Dell Perc H200:
lvcreate --name=performance-test --size=20G --stripes=6 vg0
Dom0
===================================================================================================
Default Debian Squeeze 32 Bit Kernel 64Bit HV:
1GB Ram / fixed / ballooning disabled / all cpus / no pinning
root@akaar:~# uname -a
Linux akaar 2.6.32-5-xen-686 #1 SMP Mon Mar 26 10:32:49 UTC 2012 i686 GNU/Linux
root@akaar:~# xm info
host : akaar
release : 2.6.32-5-xen-686
version : #1 SMP Mon Mar 26 10:32:49 UTC 2012
machine : i686
nr_cpus : 24
nr_nodes : 2
cores_per_socket : 6
threads_per_core : 2
cpu_mhz : 2666
hw_caps :
bfebfbff:2c100800:00000000:00001f40:029ee3ff:00000000:00000001:00000000
virt_caps : hvm hvm_directio
total_memory : 98291
free_memory : 95010
node_to_cpu : node0:0,2,4,6,8,10,12,14,16,18,20,22
node1:1,3,5,7,9,11,13,15,17,19,21,23
node_to_memory : node0:47110
node1:47899
node_to_dma32_mem : node0:0
node1:2990
max_node_id : 1
xen_major : 4
xen_minor : 0
xen_extra : .1
xen_caps : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32
hvm-3.0-x86_32p hvm-3.0-x86_64
xen_scheduler : credit
xen_pagesize : 4096
platform_params : virt_start=0xf9c00000
xen_changeset : unavailable
xen_commandline : placeholder dom0_mem=1024M
cc_compiler : gcc version 4.4.5 (Debian 4.4.5-8)
cc_compile_by : waldi
cc_compile_domain : debian.org
cc_compile_date : Mon Nov 7 09:16:11 CET 2011
xend_config_format : 4
root@akaar:~# xm list
Name ID Mem VCPUs State Time(s)
Domain-0 0 997 24 r----- 1080.2
guinan 2 4096 4 -b---- 0.0
root@akaar:~# xm vcpu-list
Name ID VCPU CPU State Time(s) CPU Affinity
Domain-0 0 0 20 -b- 747.4 any cpu
Domain-0 0 1 17 -b- 80.2 any cpu
Domain-0 0 2 12 -b- 105.4 any cpu
Domain-0 0 3 19 -b- 49.0 any cpu
Domain-0 0 4 4 -b- 30.7 any cpu
Domain-0 0 5 13 -b- 35.9 any cpu
Domain-0 0 6 21 -b- 52.3 any cpu
Domain-0 0 7 23 -b- 37.9 any cpu
Domain-0 0 8 2 -b- 26.9 any cpu
Domain-0 0 9 7 -b- 32.7 any cpu
Domain-0 0 10 14 -b- 34.8 any cpu
Domain-0 0 11 16 -b- 26.2 any cpu
Domain-0 0 12 10 -b- 23.7 any cpu
Domain-0 0 13 8 -b- 38.7 any cpu
Domain-0 0 14 5 -b- 34.8 any cpu
Domain-0 0 15 11 -b- 30.3 any cpu
Domain-0 0 16 3 -b- 29.3 any cpu
Domain-0 0 17 18 -b- 41.2 any cpu
Domain-0 0 18 14 -b- 41.4 any cpu
Domain-0 0 19 1 -b- 45.6 any cpu
Domain-0 0 20 6 r-- 43.6 any cpu
Domain-0 0 21 15 -b- 29.2 any cpu
Domain-0 0 22 0 -b- 23.2 any cpu
Domain-0 0 23 7 -b- 30.5 any cpu
guinan 2 0 9 -b- 72.1 any cpu
guinan 2 1 15 -b- 2.9 any cpu
guinan 2 2 19 -b- 7.4 any cpu
guinan 2 3 13 -b- 6.0 any cpu
=========================================================================================================
DomU
=========================================================================================================
debian Squeeze 64Bit 1GB RAM / 4 vcpus / no pinning:
root@guinan:~# uname -a
Linux guinan 2.6.32-5-xen-amd64 #1 SMP Thu Mar 22 21:14:26 UTC 2012 x86_64
GNU/Linux
root@guinan:~# free
total used free shared buffers cached
Mem: 1049180 227444 821736 0 20060 73712
-/+ buffers/cache: 133672 915508
Swap: 2101176 0 2101176
Attach Storage to DomU guinan
root@akaar:~# xm block-attach guinan phy:/dev/vg0/performance-test xvdc1 w
lvcreate --name=performance-test --size=20G --stripes=6 vg0
Cheers
Ulli
--
Ulrich Hochholdinger
Bereichsleiter Infrastruktur
Netpioneer GmbH, Beiertheimer Allee 18, 76137 Karlsruhe
Geschäftsführer: Jürgen Diller
HRB: 107521 Handelsregister Mannheim
Tel: 0721 / 9 20 60 90
Fax: 0721 / 9 20 60 30
E-Mail: Ulrich.Hochholdinger@xxxxxxxxxxxxx
www: http://www.netpioneer.de
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