Hello all, I've implemented a block device which throttles block I/O bandwidth, which I called dm-ioband, and been trying to throttle I/O bandwidth on KVM environment. But unfortunately it doesn't work well, the number of issued I/Os is not according to the bandwidth setting. On the other hand, I got the good result when accessing directly to the local disk on the local machine. I'm not so familiar with KVM. Could anyone give me any advice? For dm-ioband details, please see the website at http://people.valinux.co.jp/~ryov/dm-ioband/ The number of issued I/Os -------------------------------------------------------------- | device | sda11 | sda12 | | weight setting | 80% | 20% | |----------------------+-------------------+-------------------| | KVM | I/Os | 4397 | 2902 | | | ratio to total | 60.2% | 39.8% | |-----+----------------+-------------------+-------------------| |local| I/Os | 5447 | 1314 | | | ratio to total | 80.6% | 19.4% | -------------------------------------------------------------- The test environment and the procedure are as follow: o Prepare two partitions sda11 and sda12. o Create two bandwidth control devices, each device is mapped to the sda11 and sda12 respectively. o Give weights of 80 and 20 to each bandwidth control device respectively. o Run two virtual machines, the virtual machine's disk is mapped to the each bandwidth control device. o Run 128 processes issuing random read/write direct I/O with 4KB data on each virtual machine at the same time respectively. o Count up the number of I/Os which have done in 60 seconds. Access through KVM +---------------------------+ +--------------------------+ | Virtual Machine 1 (VM1) | | Virtual Machine 2 (VM2) | | in cgroup "ioband1" | | in cgroup "ioband2" | | | | | | Read/Write with O_DIRECT | | Read/Write with O_DIRECT | | process x 128 | | process x 128 | | | | | | | | V | | V | | /dev/vda1 | | /dev/vda1 | +-------------|-------------+ +-------------|------------+ +-------------V---------------------------------V------------+ | /dev/mapper/ioband1 | /dev/mapper/ioband2 | | 80% for cgroup "ioband1" | 20% for cgroup "ioband2" | | | | | Control I/O bandwidth according to the cgroup tasks | +-------------|---------------------------------|------------+ +-------------V-------------+ +-------------|------------+ | /dev/sda11 | | /dev/sda12 | +---------------------------+ +--------------------------+ Direct access +---------------------------+ +--------------------------+ | cgroup "ioband1" | | cgroup "ioband2" | | | | | | Read/Write with O_DIRECT | | Read/Write with O_DIRECT | | process x 128 | | process x 128 | | | | | | | +-------------|-------------+ +-------------|------------+ +-------------V---------------------------------V------------+ | /dev/mapper/ioband1 | /dev/mapper/ioband2 | | 80% for cgroup "ioband1" | 20% for cgroup "ioband2" | | | | | Control I/O bandwidth according to the cgroup tasks | +-------------|---------------------------------|------------+ +-------------V-------------+ +-------------|------------+ | /dev/sda11 | | /dev/sda12 | +---------------------------+ +--------------------------+ Thanks, Ryo Tsuruta -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
