|
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-users] Disk-I/O Performance DomU vs Dom0
Hi,what says dom0 dmesg about disk cache (write, read) of each disk behind Perc 200? We had similar problem, we followed instructions at http://blog.slucas.fr/en/tips/esxi-perc-h200-slow and then the performance dom0 vs. domU was close the same. (but our real numbers were much lower, ? only two disks mirror) Regards K. Dne 6.4.2012 15:38, Keeler, Matthew J. napsal(a): Hi Ulli, I have recently been doing some disk performance benchmarking of various Xen configurations using HVMs, PVHVMs and PVMs. I have been using the bonnie++ benchmark to do the testing and have come up with pretty much the same results you have. HVMs are about 25% of the performance of the native machine, PVHVMs are about 30-35% of the native performance and PVMs are around 50-60% of the native performance. This is when doing the block reads and writes (character reads and writes have performance numbers in the 85-95% range). I would also like to know why this is. Supposedly disk IO with PVHVMs and PVMs should be close to native performance according to graphs you can find on the internet, however this does not line up with the actual performance I have been experiencing. Several threads on this mailing list recommend people to use PVHVMs as they should see massive performance increases. Is there a particular workload that it has a meaningful impact when switching to PVHVMs? So far in my testing it seems like Xen cannot be used if you require disk intensive operations. Matt Keeler -----Original Message----- From: xen-users-bounces@xxxxxxxxxxxxx [mailto:xen-users-bounces@xxxxxxxxxxxxx] On Behalf Of Ulrich Hochholdinger Sent: Friday, April 06, 2012 6:15 AM To: xen-users@xxxxxxxxxxxxx Subject: [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 _______________________________________________ Xen-users mailing list Xen-users@xxxxxxxxxxxxx http://lists.xen.org/xen-users
|
 |
Lists.xenproject.org is hosted with RackSpace, monitoring our |