Balg, Andreas
2010-Aug-06 12:06 UTC
[Xen-users] Impressive Performance Problems with Small-Files /Small Blocksizes
hello everybody, during some extensive benchmarking for an evaluation we found some issues with i/o-performance and also memory bandwidth of Xen 3.4.2 (using XCP-0.5) running on a quite up-to-date and performant Dell-R610 Server (2 x Xeon E5620, 16G RAM, 4 x SATA 15K HDD''s - RAID 5): - Especially for small block sizes (below 32k) the I/O is very poor. to give some figures: The same Benchmark "time iozone -az -i0 -i1 -i2 -i8 -Rb results.xls" Runs around 3 Minutes on the bare Hardware, around 30 Minutes in a KVM-VM and more than 1 hour(!) in a xen VM - See attached graphs and focus on the front of the diagram (red and blue "foot" of the xen graph) What I''d like to know is, if this is be a glitch in a device driver, an error in our configuration or might be eliminated in any other way using a workaround or other version. Or is this a proble of the differences in Design or just nobody noticed it so far and it should be lokked at by the developers. Without these two significant problems Xen would outperform kvm in almost any possible manner .... Best regards Andreas -- ----------------------------------------------------------------------------- XiNCS GmbH MwST-Nr: 695 740 Schmidshaus 118 HR-Nr: CH-300.4.015.621-9 CH-9064 Hundwil AR Webseite: http://www.xincs.eu AGB: http://www.xincs.eu/agb.html Tel. +41 (0)31 526 50 95 ----------------------------------------------------------------------------- _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users