===== some benchmarking =====
== Testimonials / What ressources to benchmark and how? ==
     * network-i/o: netcat -l -p 2222 >/dev/null & dd if=/dev/zero bs=512M count=10 |netcat 10.0.0.1 2222
     * disk i/o random: iozone, bonnie++
     * disk i/o block: time bash -c 'dd if=/dev/zero of=testfile bs=512M count=4; sync;'
     * ram i/o, pure userspace/cpu-power: kernelunzipping to ram, kernelcompilation in ram, ubench

== Testcases ==
     * hvm/nas/net:   domU is in a file on attached nfs in HVM-mode, no paradrivers
     * hvmp/nas/net:  domU is in a file on attached nfs in HVM-mode, paradrivers
     * para/nas/net:  domU is in a file on attached nfs
     * para/lvm/san:  domU is in a logical volume on SAN
     * para/file/ram: domU is in a file on a dom0-ram
     * para/lvm/iscsi:domU is in a logical volume on iscsi
     * para/xfs/iscsi:domU is in a file on an xfs-filesystem on iscsi
     * para/lvm/disc: domU is in a logical volume on the local disk of dom0
     * para/xfs/disc: domU is in a file on an xfs-filesystem on the local disk of dom0
     * dom0/xfs/disc: tests on the dom0 (using internal sas-discs)
     * bare/xfs/disc: bare metal linux without xen-kernel

== results ==
^                                         ^  hvm^ hvmp^      paravirtualized domU           ^^^^^^^ dom0^ bare^
^                                         ^  nas^  nas^  nas^  lvm^ file^   lvm^   xfs^  lvm^  xfs^  xfs^  xfs^
^                                         ^  net^  net^  net^  san^  ram^ iscsi^ iscsi^ disc^ disc^ disc^ disc^
|network throughput domU->dom0 in Mb/s    |    7|   84|  230|  229|  231|   221|   226|  230|  231|  246|  344|
|network throughput dom0->domU in Mb/s    |   21|  122|   97|  110|   96|    93|    93|   98|   97|  246|  344|
|latency for icmp domU<->dom0 in ms       |   .2|   .1|   .1|   .1|   .1|    .1|    .1|   .1|   .1|  .03|  .01|
|time tar xjf linux-2.6.19.tar.bz2 in s   |   17|   14|   25|   18|   18|    17|    15|   13|   18|   16|   13|
|time make -j8 bzImage modules (real in s)| 1241| 1257|  561|  547|  560|   555|   556|  559|  559|  593|  465|
|time it takes to write a 2GB blockfile   |   17|   72|   40|   16|    8|    42|    48|  139|   65|   36|   32|

== notice ==
    * OS was SuSE SLES10SP1 amd64 with current patches as of september 2007
    * kernel extraction and compiling was done in ram of the domU
    * kernel compilation was done w/ 4 cpus pinned to the domU/dom0 and warm cache, 8GB ram
    * notice: cant test how tap:aio instead of file behaves since sles10sp1 xen doesnt support it apparently
    * here i used the disc the domU was running on for testing. Below is a test for a disc without partitiontable/filesystem, just blockdevice handed through.

  * conclusion: many values dont make much sense. random i/o also hasnt been tested yet. One should benchmark having a specific environment in mind.



===== some more benchmarking =====
What was benched here: raw i/o throughput. Just wanted to see how much performance-overhad a xen-domU has compared to the dom0 under it. Bevore testing i filled up on a host a partition on local harddiscs with data, and compared this to filling up a lvm-volume: both values are the same as expected. Commands used for testing now:
<code>
# in dom0:
time bash -c 'dd if=/dev/zero of=/dev/system/lv_ch_perftest bs=512M count=16; sync;'
# this writes 8GB of data to the logical volume and syncs it. 

# in domU, after handing the lv_ch_perftest over as xvdb:
time bash -c 'dd if=/dev/zero of=/dev/xvdb bs=512M count=16; sync;'
</code>