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Bug 1978873

Summary: guest dirty-rate calculated is not accurate when loading stress using stress cmd
Product: Red Hat Enterprise Linux 9 Reporter: Lili Zhu <lizhu>
Component: qemu-kvmAssignee: Leonardo Bras <leobras>
qemu-kvm sub component: Live Migration QA Contact: Li Xiaohui <xiaohli>
Status: CLOSED WONTFIX Docs Contact:
Severity: unspecified    
Priority: low CC: chayang, dgilbert, fjin, jinzhao, juzhang, leobras, lmen, mdean, peterx, quintela, virt-maint
Version: 9.0Flags: pm-rhel: mirror+
Target Milestone: rc   
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard:
Fixed In Version: Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2023-01-03 07:27:55 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:

Description Lili Zhu 2021-07-03 06:39:17 UTC
Description of problem:
guest dirty-rate calculated is not accurate when loading stress using stress cmd

Version-Release number of selected component (if applicable):
qemu-kvm-6.0.0-19.module+el8.5.0+11385+6e7d542e.x86_64

How reproducible:
100%

Steps to Reproduce:
[In guest]# stress --vm 1 --vm-bytes 40M
[On host]# virsh domdirtyrate-calc avocado-vt-vm1 
Start to calculate domain's memory dirty rate successfully.

# virsh domstats avocado-vt-vm1 --dirtyrate 
Domain: 'avocado-vt-vm1'
  dirtyrate.calc_status=2
  dirtyrate.calc_start_time=348414
  dirtyrate.calc_period=1
  dirtyrate.megabytes_per_second=4
(The dirtyrate is not more than 10MiB/s)

Expected results:
The dirty rate calculated should be around 40MiB/s


Additional info:
For the other info, please check:
https://bugzilla.redhat.com/show_bug.cgi?id=1812723#c20

Comment 1 Li Xiaohui 2021-07-05 07:46:09 UTC
When I use stress tool to calculate dirty rate before and during migration, get strange results as followings(qemu-kvm-6.0.0-19.module+el8.5.0+11385+6e7d542e.x86_64):

1.in vm: 
# stress --vm 1 --vm-bytes 40M
2.before migration, query dirty rate many times, it's around 6MBps:
{"execute":"calc-dirty-rate", "arguments": {"calc-time": 1}}
{"return": {}}
{"execute":"query-dirty-rate"}
{"return": {"status": "measured", "dirty-rate": 6, "start-time": 1035316, "calc-time": 1}}
3.during migration is active, check dirty rate many times, it's mostly more than 100MBps:
(qemu) info migrate
globals:
store-global-state: on
only-migratable: off
send-configuration: on
send-section-footer: on
decompress-error-check: on
clear-bitmap-shift: 18
Migration status: active
total time: 427250 ms
expected downtime: 413 ms
setup: 2 ms
transferred ram: 49035815 kbytes
throughput: 945.20 mbps
remaining ram: 38792 kbytes
total ram: 4211528 kbytes
duplicate: 1369381 pages
skipped: 0 pages
normal: 12232039 pages
normal bytes: 48928156 kbytes
dirty sync count: 3228
page size: 4 kbytes
multifd bytes: 0 kbytes
pages-per-second: 28980
dirty pages rate: 29275 pages        ----> Query migrate data many times, always around 30000 pages



So seems the STRESS tool is not ideal for migration to load stress when we test dirty-rate feature.

Comment 2 Li Xiaohui 2021-07-05 08:55:36 UTC
As we know, stressapptest tool is better suited for migration than the stress tool when we test dirty-rate feature, and there's no other issues when we use stressapptest testing as below comment.
https://bugzilla.redhat.com/show_bug.cgi?id=1812723#c17

Comment 3 Li Xiaohui 2021-07-12 11:05:15 UTC
Hi Dave,
Could you help check Comment 1 & Comment 2 from me? Shall we update calculating dirty-rate cases to add stress tool as a test tool besides stressapptest?

Comment 4 John Ferlan 2021-07-22 18:29:24 UTC
Assigned to Meirav for initial triage per bz process and age of bug created or assigned to virt-maint without triage.

Comment 5 John Ferlan 2021-09-08 21:28:13 UTC
Move RHEL-AV bugs to RHEL9. If necessary to resolve in RHEL8, then clone to the current RHEL8 release.

Comment 6 John Ferlan 2022-10-20 21:34:14 UTC
Leo - between this bug and bug 1919863, are there commonalities? Any chance either one can be worked on / resolved for RHEL 9.2?  I'm trying to stay ahead of problems that will end up on the "aging" close wontfix list.

Comment 9 RHEL Program Management 2023-01-03 07:27:55 UTC
After evaluating this issue, there are no plans to address it further or fix it in an upcoming release.  Therefore, it is being closed.  If plans change such that this issue will be fixed in an upcoming release, then the bug can be reopened.