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Description of problem: a maximum value can be set by blkiotune , but can not be checked in cgroup. Version-Release number of selected component (if applicable): kernel-3.10.0-203.el7.x86_64 qemu-kvm-rhev-2.1.2-8.el7.x86_64 libvirt-1.2.8-6.el7.x86_64 How reproducible: 100% Steps to Reproduce: # virsh list Id Name State ---------------------------------------------------- 29 r7 running 1> for device_read/write_iops_sec , set value=4294967295 , set successfully. but can not be checked in cgroup. 1.1> set the value and check using blkiotune command # virsh blkiotune r7 --device-read-iops-sec /dev/sda,4294967295 --device-write-iops-sec /dev/sda,4294967295 [root@184 ~]# virsh blkiotune r7 weight : 500 device_weight : device_read_iops_sec: /dev/sda,4294967295 device_write_iops_sec: /dev/sda,4294967295 device_read_bytes_sec: device_write_bytes_sec: 1.2> check the value in the cgroup , it has nothing # cat /sys/fs/cgroup/blkio/machine.slice/machine-qemu\\x2dr7.scope/blkio.throttle.read_iops_device # cat /sys/fs/cgroup/blkio/machine.slice/machine-qemu\\x2dr7.scope/blkio.throttle.write_iops_device 2> for device_read/write_bytes_sec , set value= 18446744073709551615, set successfully. but can not be checked in cgroup. 2.1> set the value and check using blkiotune command # virsh blkiotune r7 --device-read-bytes-sec /dev/sda,18446744073709551615 --device-write-bytes-sec /dev/sda,18446744073709551615 # virsh blkiotune r7 weight : 500 device_weight : device_read_iops_sec: /dev/sda,4294967295 device_write_iops_sec: /dev/sda,4294967295 device_read_bytes_sec: /dev/sda,18446744073709551615 device_write_bytes_sec: /dev/sda,18446744073709551615 2.2> check the value in cgroup , it has nothing # cat /sys/fs/cgroup/blkio/machine.slice/machine-qemu\\x2dr7.scope/blkio.throttle.read_bps_device # cat /sys/fs/cgroup/blkio/machine.slice/machine-qemu\\x2dr7.scope/blkio.throttle.write_bps_device 3>check domain XML , it has the value . # virsh dumpxml r7 | grep blkiotune -A 8 <blkiotune> <device> <path>/dev/sda</path> <read_iops_sec>4294967295</read_iops_sec> <write_iops_sec>4294967295</write_iops_sec> <read_bytes_sec>18446744073709551615</read_bytes_sec> <write_bytes_sec>18446744073709551615</write_bytes_sec> </device> </blkiotune> Actual results: As above , the value can be set by blkiotune and set successfully in the domain XML , but it has nothing in cgroup. Expected results: the value set by blkiotune can be checked in cgroup. Additional info:
Patch proposed upstream: https://www.redhat.com/archives/libvir-list/2015-August/msg00065.html
Verified version: libvirt-1.2.17-8.el7.x86_64 qemu-kvm-rhev-2.3.0-22.el7.x86_64 verified steps: 1.define and start a guest, check blkiotune value. # virsh blkiotune r72 weight : 1000 device_weight : device_read_iops_sec: device_write_iops_sec: device_read_bytes_sec: device_write_bytes_sec: 1.1. set a iops value that kernel accepts, but does not set them. set the value # virsh blkiotune r72 --device-read-iops-sec /dev/sdb,4294967295 get the value via blkiotune # virsh blkiotune r72 weight : 1000 device_weight : device_read_iops_sec: device_write_iops_sec: device_read_bytes_sec: device_write_bytes_sec: check in cgroup, Nothing ouput # cat /sys/fs/cgroup/blkio/machine.slice/machine-qemu\\x2dr72.scope/blkio.throttle.read_iops_device check domian xml, Nothing output. # virsh dumpxml r72 | grep blkiotune -A 3 1.2 set a normal value that kernel accpets and will set them in cgroup. # virsh blkiotune r72 --device-read-iops-sec /dev/sdb,4294967294 check in cgroup # cat /sys/fs/cgroup/blkio/machine.slice/machine-qemu\\x2dr72.scope/blkio.throttle.read_iops_device 8:16 4294967294 check via blkiotune # virsh blkiotune r72 weight : 1000 device_weight : device_read_iops_sec: /dev/sdb,4294967294 device_write_iops_sec: device_read_bytes_sec: device_write_bytes_sec: check in domian xml : # virsh dumpxml r72 | grep blkiotune -A 3 <blkiotune> <device> <path>/dev/sdb</path> <read_iops_sec>4294967294</read_iops_sec> -- </blkiotune> 2. set a bps value that kernel accepts, but does not set them. # virsh blkiotune r72 --device-write-bytes-sec /dev/sdb,18446744073709551615 get the value via blkiotune # virsh blkiotune r72 weight : 1000 device_weight : device_read_iops_sec: device_write_iops_sec: device_read_bytes_sec: device_write_bytes_sec: check in cgroup, Nothing ouput # cat /sys/fs/cgroup/blkio/machine.slice/machine-qemu\\x2dr72.scope/blkio.throttle.write_bps_device check domian xml, Nothing output. # virsh dumpxml r72 | grep blkiotune -A 3 2.1 set a normal value that kernel accpets and will set them in cgroup. # virsh blkiotune r72 --device-write-bytes-sec /dev/sdb,18446744073709551614 check in cgroup # cat /sys/fs/cgroup/blkio/machine.slice/machine-qemu\\x2dr72.scope/blkio.throttle.write_bps_device 8:16 18446744073709551614 check via blkiotune # virsh blkiotune r72 weight : 1000 device_weight : device_read_iops_sec: device_write_iops_sec: device_read_bytes_sec: device_write_bytes_sec: /dev/sdb,18446744073709551614 check in domain xml # virsh dumpxml r72 | grep blkiotune -A 5 <blkiotune> <device> <path>/dev/sdb</path> <write_bytes_sec>18446744073709551614</write_bytes_sec> </device> </blkiotune> Also tested with lxc using same steps as above. Now the values set via blkiotune are in sync with cgroup. Move to verified.
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://rhn.redhat.com/errata/RHBA-2015-2202.html