Bug 1741825

Summary:	[cgroup_v2] Error happened and xml not changed when use blkiotune to set blk cgroup values
Product:	Red Hat Enterprise Linux 8	Reporter:	yisun
Component:	libvirt	Assignee:	Pavel Hrdina <phrdina>
Status:	CLOSED ERRATA	QA Contact:	yisun
Severity:	medium	Docs Contact:
Priority:	unspecified
Version:	8.1	CC:	jdenemar, knoel, phrdina, rbalakri, wchadwic, yalzhang, yisun
Target Milestone:	rc	Flags:	pm-rhel: mirror+
Target Release:	8.1
Hardware:	x86_64
OS:	Linux
Whiteboard:
Fixed In Version:	libvirt-4.5.0-33.el8	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:	1734353	Environment:
Last Closed:	2019-11-05 20:51:11 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:	1734353
Bug Blocks:	1689297

Description yisun 2019-08-16 07:49:41 UTC

+++ This bug was initially created as a clone of Bug #1734353 +++

Description:
[cgroup_v2] Error happened and xml not changed when use blkiotune to set blk cgroup values

Versions:
libvirt-5.5.0-2.module+el8.1.0+3773+7dd501bf.x86_64

How reproducible:
100%

Steps:
0. Enable cgroup v2
1. Having block device /dev/sda on host:
[root@ibm-x3250m6-06 ~]# lsblk
NAME                           MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda                              8:0    0 931.5G  0 disk
...

2. Use blkiotune to set "--device-read-iops-sec" to a running vm
[root@ibm-x3250m6-06 ~]# virsh blkiotune avocado-vt-vm1 --device-read-iops-sec /dev/sda,1234
error: Unable to change blkio parameters
error: internal error: Unable to parse 'rbps=max wbps=max riops=1234 wiops=max' as an integer
<==== error produced

[root@ibm-x3250m6-06 ~]# virsh dumpxml avocado-vt-vm1 | grep 1234  | wc -l
0
<==== xml not changed

[root@ibm-x3250m6-06 ~]# cat /sys/fs/cgroup/machine.slice/machine-qemu\\x2d1\\x2davocado\\x2dvt\\x2dvm1.scope/io.max 
8:0 rbps=max wbps=max riops=1234 wiops=max
<==== but corresponding cgroup controller value changed as expected

3. set "--device-read-bytes-sec", same as step 2
[root@ibm-x3250m6-06 ~]# virsh blkiotune avocado-vt-vm1 --device-read-bytes-sec /dev/sda,5678
error: Unable to change blkio parameters
error: internal error: Unable to parse 'rbps=5678 wbps=max riops=1234 wiops=4321' as an integer

[root@ibm-x3250m6-06 ~]# virsh dumpxml avocado-vt-vm1 | grep 5678 | wc -l
0

[root@ibm-x3250m6-06 ~]# cat /sys/fs/cgroup/machine.slice/machine-qemu\\x2d1\\x2davocado\\x2dvt\\x2dvm1.scope/io.max 
8:0 rbps=5678 wbps=max riops=1234 wiops=4321

4. set "--device-write-bytes-sec", same as step 2
[root@ibm-x3250m6-06 ~]# virsh blkiotune avocado-vt-vm1 --device-write-bytes-sec /dev/sda,8765
error: Unable to change blkio parameters
error: internal error: Unable to parse 'rbps=5678 wbps=8765 riops=1234 wiops=4321' as an integer

[root@ibm-x3250m6-06 ~]# virsh dumpxml avocado-vt-vm1 | grep 8765 | wc -l
0

[root@ibm-x3250m6-06 ~]# cat /sys/fs/cgroup/machine.slice/machine-qemu\\x2d1\\x2davocado\\x2dvt\\x2dvm1.scope/io.max 
8:0 rbps=5678 wbps=8765 riops=1234 wiops=4321


5. setting "--device-write-iops-sec" is OK
[root@ibm-x3250m6-06 ~]# virsh blkiotune avocado-vt-vm1 --device-write-iops-sec /dev/sda,4321
[root@ibm-x3250m6-06 ~]# cat /sys/fs/cgroup/machine.slice/machine-qemu\\x2d1\\x2davocado\\x2dvt\\x2dvm1.scope/io.max 
8:0 rbps=max wbps=max riops=1234 wiops=4321
[root@ibm-x3250m6-06 ~]# virsh dumpxml avocado-vt-vm1 | grep 4321 | wc -l
1


Expected result:
No error happened and xml should be changed correctly.

--- Additional comment from  on 2019-08-01 06:56:58 UTC ---

When set 2 or more devices concurrently, the error will block the 2nd and rest settings, as follow:
$ lsblk  | egrep "sda |sdb "
sda             8:0    0 465.8G  0 disk 
sdb             8:16   0  1000M  0 disk 


$ pwd
/sys/fs/cgroup/machine.slice/machine-qemu\x2d9\x2davocado\x2dvt\x2dvm1.scope

$ virsh blkiotune avocado-vt-vm1 --device-read-iops-sec /dev/sda,321321,/dev/sdb,123123
error: Unable to change blkio parameters
error: internal error: Unable to parse 'rbps=max wbps=max riops=321321 wiops=max' as an integer

$ cat io.max 
8:0 rbps=max wbps=max riops=321321 wiops=max
<===== here, only the /dev/sda setting takes effect.

Comment 1 yisun 2019-08-16 07:51:01 UTC

reproduced on: libvirt-4.5.0-31.module+el8.1.0+3808+3325c1a3.x86_64
so clone to rhel8.1 branch

Comment 8 yisun 2019-08-30 10:15:04 UTC

Verified on libvirt-4.5.0-33.module+el8.1.0+4066+0f1aadab.x86_64 and PASSED

1. Set --device-read-iops-sec 
 [root@hp-dl320eg8-07 machine-qemu\x2d2\x2davocado\x2dvt\x2dvm1.scope]# virsh blkiotune avocado-vt-vm1 --device-read-iops-sec /dev/sda,123

[root@hp-dl320eg8-07 machine-qemu\x2d2\x2davocado\x2dvt\x2dvm1.scope]# virsh dumpxml avocado-vt-vm1 | grep 123
      <read_iops_sec>123</read_iops_sec>

[root@hp-dl320eg8-07 machine-qemu\x2d2\x2davocado\x2dvt\x2dvm1.scope]# cat io.max
8:0 rbps=max wbps=max riops=123 wiops=max

2. Set --device-read-iops-sec 
[root@hp-dl320eg8-07 machine-qemu\x2d2\x2davocado\x2dvt\x2dvm1.scope]# virsh blkiotune avocado-vt-vm1 --device-read-bytes-sec /dev/sda,5678

[root@hp-dl320eg8-07 machine-qemu\x2d2\x2davocado\x2dvt\x2dvm1.scope]# virsh dumpxml avocado-vt-vm1 | grep 5678
      <read_bytes_sec>5678</read_bytes_sec>
[root@hp-dl320eg8-07 machine-qemu\x2d2\x2davocado\x2dvt\x2dvm1.scope]# cat io.max
8:0 rbps=5678 wbps=max riops=123 wiops=max

3. Set --device-write-bytes-sec 
[root@hp-dl320eg8-07 machine-qemu\x2d2\x2davocado\x2dvt\x2dvm1.scope]# virsh blkiotune avocado-vt-vm1 --device-write-bytes-sec /dev/sda,8765

[root@hp-dl320eg8-07 machine-qemu\x2d2\x2davocado\x2dvt\x2dvm1.scope]# virsh dumpxml avocado-vt-vm1 | grep 8765
      <write_bytes_sec>8765</write_bytes_sec>
[root@hp-dl320eg8-07 machine-qemu\x2d2\x2davocado\x2dvt\x2dvm1.scope]# cat io.max
8:0 rbps=5678 wbps=8765 riops=123 wiops=max

4. Set --device-write-iops-sec
[root@hp-dl320eg8-07 machine-qemu\x2d2\x2davocado\x2dvt\x2dvm1.scope]# virsh blkiotune avocado-vt-vm1 --device-write-iops-sec /dev/sda,4321

[root@hp-dl320eg8-07 machine-qemu\x2d2\x2davocado\x2dvt\x2dvm1.scope]# virsh dumpxml avocado-vt-vm1 | grep 4321
      <write_iops_sec>4321</write_iops_sec>
[root@hp-dl320eg8-07 machine-qemu\x2d2\x2davocado\x2dvt\x2dvm1.scope]# virsh blkiotune avocado-vt-vm1
weight         : 100
device_weight  :
device_read_iops_sec: /dev/sda,123
device_write_iops_sec: /dev/sda,4321
device_read_bytes_sec: /dev/sda,5678
device_write_bytes_sec: /dev/sda,8765

[root@hp-dl320eg8-07 machine-qemu\x2d2\x2davocado\x2dvt\x2dvm1.scope]# cat io.max
8:0 rbps=5678 wbps=8765 riops=123 wiops=4321

5. Set all to max
[root@hp-dl320eg8-07 machine-qemu\x2d2\x2davocado\x2dvt\x2dvm1.scope]# virsh blkiotune avocado-vt-vm1 --device-read-iops-sec /dev/sda,0 --device-read-bytes-sec /dev/sda,0 --device-write-bytes-sec /dev/sda,0 --device-write-iops-sec /dev/sda,0

[root@hp-dl320eg8-07 machine-qemu\x2d2\x2davocado\x2dvt\x2dvm1.scope]# virsh blkiotune avocado-vt-vm1
weight         : 100
device_weight  :
device_read_iops_sec:
device_write_iops_sec:
device_read_bytes_sec:
device_write_bytes_sec:

6. Set all to 1111
[root@hp-dl320eg8-07 machine-qemu\x2d2\x2davocado\x2dvt\x2dvm1.scope]# cat io.max
8:0 rbps=1111 wbps=1111 riops=max wiops=1111
[root@hp-dl320eg8-07 machine-qemu\x2d2\x2davocado\x2dvt\x2dvm1.scope]# virsh blkiotune avocado-vt-vm1 --device-read-iops-sec /dev/sda,0 --device-read-bytes-sec /dev/sda,0 --device-write-bytes-sec /dev/sda,0 --device-write-iops-sec /dev/sda,0

[root@hp-dl320eg8-07 machine-qemu\x2d2\x2davocado\x2dvt\x2dvm1.scope]# cat io.max
[root@hp-dl320eg8-07 machine-qemu\x2d2\x2davocado\x2dvt\x2dvm1.scope]# virsh blkiotune avocado-vt-vm1 --device-read-iops-sec /dev/sda,1111 --device-read-bytes-sec /dev/sda,1111 --device-write-bytes-sec /dev/sda,1111 --device-write-iops-sec /dev/sda,1111

[root@hp-dl320eg8-07 machine-qemu\x2d2\x2davocado\x2dvt\x2dvm1.scope]# virsh dumpxml avocado-vt-vm1 | grep 1111
      <read_iops_sec>1111</read_iops_sec>
      <write_iops_sec>1111</write_iops_sec>
      <read_bytes_sec>1111</read_bytes_sec>
      <write_bytes_sec>1111</write_bytes_sec>
[root@hp-dl320eg8-07 machine-qemu\x2d2\x2davocado\x2dvt\x2dvm1.scope]# cat io.max
8:0 rbps=1111 wbps=1111 riops=1111 wiops=1111

Comment 10 errata-xmlrpc 2019-11-05 20:51:11 UTC

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://access.redhat.com/errata/RHSA-2019:3345