<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:x="urn:schemas-microsoft-com:office:excel" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"> <head> <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=us-ascii"> <meta name=Generator content="Microsoft Word 12 (filtered medium)"> <style>  </style>  </head> <body lang=DE link=blue vlink=purple> <div class=Section1> Hello, I have trouble with the network performance inside my virtual machines. My KVM-Host machine is connected to a 10Gbit Network. All interfaces are configured to a mtu of 4132. On this host I have no problems and I can use the full bandwidth: # iperf -c 10.10.80.100 -w 65536 -p 12345 -t 60 -P4 [ ID] Interval Transfer Bandwidth [ 4] 0.0-60.0 sec 18.8 GBytes 2.69 Gbits/sec [ 5] 0.0-60.0 sec 15.0 GBytes 2.14 Gbits/sec [ 6] 0.0-60.0 sec 19.3 GBytes 2.76 Gbits/sec [ 3] 0.0-60.0 sec 15.1 GBytes 2.16 Gbits/sec [SUM] 0.0-60.0 sec 68.1 GBytes 9.75 Gbits/sec Inside a virtual machine don't reach this result: # iperf -c 10.10.80.100 -w 65536 -p 12345 -t 60 -P 4 [ ID] Interval Transfer Bandwidth [ 3] 0.0-60.0 sec 5.65 GBytes 808 Mbits/sec [ 4] 0.0-60.0 sec 5.52 GBytes 790 Mbits/sec [ 5] 0.0-60.0 sec 5.66 GBytes 811 Mbits/sec [ 6] 0.0-60.0 sec 5.70 GBytes 816 Mbits/sec [SUM] 0.0-60.0 sec 22.5 GBytes 3.23 Gbits/sec I only can use 3,23Gbits of 10Gbits. I use the virtio driver for all of my vms, but I have also tried to use the e1000 nic device instead. With starting the iperf performance test on multiple vms simultaneously I can use the full bandwidth of the kvm host's interface. But only one vm can't use the full bandwith. Is this a known limitation, or can I improve this performance? Does anyone have an idea how I can improve my network performance? It's very important, because I want to use the network interface to boot all vms via AOE (ATA over Ethernet). If I mount a harddisk via AOE inside a vm I get only this results: Write |CPU |Rewrite |CPU |Read |CPU 102440 |10 |51343 |5 |104249 |3 On the KVM Host I get those results on a mouted AOE Device: Write |CPU |Rewrite |CPU |Read |CPU 205597 |19 |139118 |11 |391316 |11 If I mount the AOE Device directly on the kvm-host and put a virtual harddisk-file in it I got the following results inside a vm using this harddisk-file: Write |CPU |Rewrite |CPU |Read |CPU 175140 |12 |136113 |24 |599989 |29 <o:p></o:p> Here more details about my environment: KVM Version: QEMU PC emulator version 0.12.3 (qemu-kvm-0.12.3), Copyright (c) 2003-2008 Fabrice Bellard 0.12.3+noroms-0ubuntu9 KVM Host Kernel: 2.6.32-22-server #36-Ubuntu SMP Thu Jun 3 20:38:33 UTC 2010 x86_64 GNU/Linux KVM Host OS: Distributor ID: Ubuntu Description: Ubuntu 10.04 LTS Release: 10.04 Codename: lucid KVM Guest Kernel: 2.6.32-22-server #36-Ubuntu SMP Thu Jun 3 20:38:33 UTC 2010 x86_64 GNU/Linux KVM Guest OS: Distributor ID: Ubuntu Description: Ubuntu 10.04 LTS Release: 10.04 Codename: lucid I would feel very happy if someone can help to solve my problem!<o:p></o:p> <o:p> </o:p> Best regards<o:p></o:p> <o:p> </o:p> <o:p> </o:p> <o:p> </o:p> <o:p> </o:p> <o:p> </o:p> </div> </body> </html>