Re: Awful FreeBSD 9 block IO performance in KVM
On 19/07/2012 20:27, Richard Yao 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? I'm interested in seeing if the difference is still large while writing to a raw device (dd of=/dev/xxx bs=1m count=1000) vs writing to the file system. Can you test this? signature.asc Description: OpenPGP digital signature
Re: Awful FreeBSD 9 block IO performance in KVM
On 19 July 2012 11:27, Richard Yao r...@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 ___ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to freebsd-hackers-unsubscr...@freebsd.org
Re: Awful FreeBSD 9 block IO performance in KVM
On 07/20/2012 03:44 PM, Adrian Chadd wrote: On 19 July 2012 11:27, Richard Yao r...@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 signature.asc Description: OpenPGP digital signature
Re: Awful FreeBSD 9 block IO performance in KVM
On 20 July 2012 15:26, Richard Yao r...@gentoo.org wrote: 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. Thanks for setting this up. Setting up an easily reproducible environment is by far the biggest and most helpful step here. Adrian ___ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to freebsd-hackers-unsubscr...@freebsd.org
Re: Awful FreeBSD 9 block IO performance in KVM
On 07/20/2012 06:26 PM, Richard Yao wrote: On 07/20/2012 03:44 PM, Adrian Chadd wrote: On 19 July 2012 11:27, Richard Yao r...@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 I now have FreeBSD 9.1-BETA1 installed in a virtual machine. I noticed the following in dmesg which might explain why the emulated SCSI support is so slow: da0 at sym0 bus 0 scbus2 target 0 lun 0 da0: QEMU QEMU HARDDISK 1.1. Fixed Direct Access SCSI-5 device da0: 3.300MB/s transfers da0: Command Queueing enabled da0: 409600MB (838860800 512 byte sectors: 255H 63S/T 52216C) It does not explain why virtio is slow though, although I still need to test virtio against the latest code. I will do ivan's raw block test against virtio-blk, mainly because there is no point in doing it against a device whose transfers have been capped to 3.3MB/sec. signature.asc Description: OpenPGP digital signature
