On Wed, Dec 10, 2014 at 2:10 PM, <[email protected]> wrote: > In Proxmox the storage is configured as "virtio0". > > I attached a part of dmesg: > > atapci0: <Intel PIIX3 WDMA2 controller> port > 0xc0a0-0xc0af,0x376,0x170-0x177,0x3f6,0x1f0-0x1f7 at device 1.1 on pci0 > ata0: <ATA channel 0> on atapci0 > ata1: <ATA channel 1> on atapci0 > disk scheduler: set policy of acd0 to noop > acd0: DVDROM <QEMU DVD-ROM/2.1.2> at ata1-master WDMA2 > uhci0: <Intel 82371SB (PIIX3) USB controller> port 0xc040-0xc05f irq 11 at > device 1.2 on pci0 > usbus0: controller did not stop > usbus0: <Intel 82371SB (PIIX3) USB controller> on uhci0 > pci0: <bridge> (vendor 0x8086, dev 0x7113) at device 1.3 irq 9 > vgapci0: <VGA-compatible display> mem > 0xfebf0000-0xfebf0fff,0xfc000000-0xfdffffff at device 2.0 on pci0 > vgapci0: Boot video device > virtio_pci0: <VirtIO PCI Balloon adapter> port 0xc060-0xc07f irq 11 at > device 3.0 on pci0 > virtio_pci1: <VirtIO PCI Block adapter> port 0xc000-0xc03f mem > 0xfebf1000-0xfebf1fff irq 10 at device 10.0 on pci0 > vtblk0: <VirtIO Block Adapter> on virtio_pci1 > virtio_pci1: host features: 0x71000ed4 > <EventIdx,0x10000000,NotifyOnEmpty,0x800,Topology,FlushCmd,SCSICmds,BlockSize,DiskGeometry,MaxNumSegs> > virtio_pci1: negotiated features: 0x254 > <FlushCmd,BlockSize,DiskGeometry,MaxNumSegs> > disk scheduler: set policy of vbd0 to noop >
DragonFly BSD's virtio-pci driver does not (at least 'did not') support indirect ring entries; qemu/kvm default to a 128-entry queue for each virtio-blk device; Dfly systems were regularly bandwidth limited by filling that queue; (at 64 KiB I/Os and fragmented physmem, you can only have 12-16 inflight IOs per disk). DFly also appears to not be using MSI-X for the virtio-blk device; fixing that should result in modest but real per-I/O improvements Bug: http://bugs.dragonflybsd.org/issues/2577 is related. HTH, -- vs;
