On 07/20/2012 03:44 PM, Adrian Chadd wrote: > On 19 July 2012 11:27, Richard Yao <ryao_at_gentoo.org> wrote: >> Dear Everyone, >> >> FreeBSD 9 has awful block IO performance in KVM. I have experienced it >> and others have experienced it. Someone posted slides to slideshare with >> benchmarks documenting it: >> >> http://www.slideshare.net/TakeshiHasegawa1/runningfreebsdonlinuxkvm >> >> Slides 13 and 20 are particular eye openers. Does anyone know what is wrong? > > For those watching at home - this is bad performance _with_ the virtio > drivers themselves, not just with SCSI emulation. > > Slide 17 is very telling - the operation latency is quite high. > > Richard, are you able to easily test out things on FreeBSD-HEAD guest > in a Linux KVM? If so, some of the storage/block/GEOM driver people > may be able to step up and start offering some ideas. > > Thanks, > > > > Adrian Dear Adrian, I am in the process of setting up a VM instance specifically for this. While installing it, I noticed that qemu-kvm printed 'lsi_scsi: error: ORDERED queue not implemented', which might be a clue as to why the block device performance is bad. Also, I will try testing raw disk IO for Ivan after I have it setup. Yours truly, Richard Yao
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