Bug 1151957
| Summary: | Throughput limitaion is not enforced using blkdeviotune | ||||||
|---|---|---|---|---|---|---|---|
| Product: | Red Hat Enterprise Linux 7 | Reporter: | Elad <ebenahar> | ||||
| Component: | libvirt | Assignee: | Ján Tomko <jtomko> | ||||
| Status: | CLOSED WORKSFORME | QA Contact: | Virtualization Bugs <virt-bugs> | ||||
| Severity: | high | Docs Contact: | |||||
| Priority: | unspecified | ||||||
| Version: | 7.0 | CC: | acanan, dfediuck, dyuan, ebenahar, gchaplik, rbalakri, rgolan, xuzhang, yanyang | ||||
| Target Milestone: | rc | ||||||
| Target Release: | --- | ||||||
| Hardware: | x86_64 | ||||||
| OS: | Unspecified | ||||||
| Whiteboard: | |||||||
| Fixed In Version: | Doc Type: | Bug Fix | |||||
| Doc Text: | Story Points: | --- | |||||
| Clone Of: | Environment: | ||||||
| Last Closed: | 2014-11-03 05:22:51 UTC | Type: | Bug | ||||
| Regression: | --- | Mount Type: | --- | ||||
| Documentation: | --- | CRM: | |||||
| Verified Versions: | Category: | --- | |||||
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |||||
| Cloudforms Team: | --- | Target Upstream Version: | |||||
| Embargoed: | |||||||
| Bug Depends On: | |||||||
| Bug Blocks: | 906938 | ||||||
| Attachments: |
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Elad, is this relevant for rhel 6.6 as well? I can't reliably reproduce this, but the one time it happened dd of=/dev/vdb was unable to open the device with oflag=direct. Copying to a file on a filesystem created on the hotplugged disk was reported to happen at about 500 MB/s in the guest, but it didn't go over the 1 MB/s limit in the host. It seems to me libvirt did everything right there. Are you able to use oflag=direct on the hotplugged disk? What is the XML of the attached disk? (In reply to Doron Fediuck from comment #1) > Elad, is this relevant for rhel 6.6 as well? It seems that using RHEL6.6, the blkdeviotune lomitation is enforced: Before setting the limitation, wrote to the device: [root@localhost elad]# dd if=/dev/zero of=/elad/1 oflag=direct bs=8K count=131072 131072+0 records in 131072+0 records out 1073741824 bytes (1.1 GB) copied, 114.7 s, 9.4 MB/s I set the limitation: virsh blkdeviotune vm_1 vdb --write_bytes_sec $(expr 1024 \* 1024 \* 1) Now limitation for writting to the device is enforced: [root@localhost elad]# dd if=/dev/zero of=/elad/1 oflag=direct bs=8K count=131072 ^C85275+0 records in 85275+0 records out 698572800 bytes (699 MB) copied, 693.119 s, 1.0 MB/s I'm using a RHEL6.6 host: libvirt-0.10.2-46.el6_6.1.x86_64 qemu-kvm-rhev-0.12.1.2-2.448.el6.x86_64 vdsm-4.16.7.1-1.el6ev.x86_64 So the problem is only in rhel 7? Can you provide the xml dump as asked for in comment 2? Couldn't reprodeuce the issue using RHEL7 with libvirt-daemon-1.2.8-5.el7_0.x86_64 The write limitation is enforced. Doron, As this issue doesn't reproduce, we thought maybe it is related to libvirt version ... anyway we can close as worksforme unless you find something while investigating Up to you. (In reply to Aharon Canan from comment #6) > Doron, > > As this issue doesn't reproduce, we thought maybe it is related to libvirt > version ... > > anyway we can close as worksforme unless you find something while > investigating > > Up to you. Go ahead and close. We'll re-open if needed. |
Created attachment 946266 [details] /var/log/messages and /var/log/vdsm/vdsm.log Description of problem: I tried to limit the writing to a virtual disk on a rhev hypervisor using virsh. The limitation doesn't seem to be enforced. Version-Release number of selected component (if applicable): RHEL7 libvirt-daemon-1.2.8-4.el7.x86_64 vdsm-4.16.6-1.el7.x86_64 qemu-kvm-rhev-1.5.3-60.el7_0.10.x86_64 How reproducible: Always Steps to Reproduce: 1. Start a VM via RHEVM on a RHEV hypervisor (VDSM installed on RHEL7). Install RHEL OS on the VM 2. Attach a second disk to the VM. Crate a FS on the disk and mount it 3. Perform a base-line test. In the guest, write out a large file and see the IO rate: # dd if=/dev/zero of=/elad/1 oflag=direct bs=8K count=131072 4. Limit the write troughput: # virsh blkdeviotune 1 vda --write_bytes_sec $(expr 1024 \* 1024 \* 10) # virsh blkdeviotune 1 vda 5. Now test the throughput, execute the same 'dd' test from step3: # dd if=/dev/zero of=/elad/1 oflag=direct bs=8K count=131072 Actual results: Without the limitation and with it, the troughput reamins the same, even though it is supposed to be limited: Before limitation configured (step3): [root@localhost ~]# dd if=/dev/zero of=/elad/1 oflag=direct bs=8K count=131072 122707+0 records in 122706+0 records out 1005207552 bytes (1.0 GB) copied, 77.1332 s, 13.0 MB/s Limitation is configured (step5): # virsh blkdeviotune 1 vdc --write_bytes_sec $(expr 1024 \* 1024 \* 1) virsh # blkdeviotune 1 vdc Please enter your authentication name: elad Please enter your password: total_bytes_sec: 0 read_bytes_sec : 0 write_bytes_sec: 1048576 total_iops_sec : 0 read_iops_sec : 0 write_iops_sec : 0 [root@localhost ~]# dd if=/dev/zero of=/elad/1 oflag=direct bs=8K count=131072 122707+0 records in 122706+0 records out 1005207552 bytes (1.0 GB) copied, 77.0214 s, 13.1 MB/s Expected results: Limitation should be enforced Additional info: /var/log/messages and /var/log/vdsm/vdsm.log (Can't find more logs of libvirt under /var/log/libvirt/)