Note: This bug is displayed in read-only format because
the product is no longer active in Red Hat Bugzilla.
RHEL Engineering is moving the tracking of its product development work on RHEL 6 through RHEL 9 to Red Hat Jira (issues.redhat.com). If you're a Red Hat customer, please continue to file support cases via the Red Hat customer portal. If you're not, please head to the "RHEL project" in Red Hat Jira and file new tickets here. Individual Bugzilla bugs in the statuses "NEW", "ASSIGNED", and "POST" are being migrated throughout September 2023. Bugs of Red Hat partners with an assigned Engineering Partner Manager (EPM) are migrated in late September as per pre-agreed dates. Bugs against components "kernel", "kernel-rt", and "kpatch" are only migrated if still in "NEW" or "ASSIGNED". If you cannot log in to RH Jira, please consult article #7032570. That failing, please send an e-mail to the RH Jira admins at rh-issues@redhat.com to troubleshoot your issue as a user management inquiry. The email creates a ServiceNow ticket with Red Hat. Individual Bugzilla bugs that are migrated will be moved to status "CLOSED", resolution "MIGRATED", and set with "MigratedToJIRA" in "Keywords". The link to the successor Jira issue will be found under "Links", have a little "two-footprint" icon next to it, and direct you to the "RHEL project" in Red Hat Jira (issue links are of type "https://issues.redhat.com/browse/RHEL-XXXX", where "X" is a digit). This same link will be available in a blue banner at the top of the page informing you that that bug has been migrated.
Description of problem:
dirty-rate is divided by calc-time when calculate guest dirty-rate
Version-Release number of selected component (if applicable):
host info:
kernel-4.18.0-275.el8.x86_64&qemu-kvm-5.2.0-3.module+el8.4.0+9499+42e58f08.x86_64
guest info:
kernel-4.18.0-275.el8.x86_64
How reproducible:
100%
Steps to Reproduce:
1.Boot a guest on src host, please see qemu command[1];
2.Run stress in guest
# stressapptest -M 200 -s 100000
3.Query dirty rate via qmp cmds
(1)Scenario 1: set calc-time to 3:
{"execute":"calc-dirty-rate", "arguments": {"calc-time": 3}}
(2)Scenario 2: set calc-time to 1:
{"execute":"calc-dirty-rate", "arguments": {"calc-time": 1}}
after (1) or (2), check dirty rate:
{"execute":"query-dirty-rate"}
Actual results:
After step 3, get different dirty rate between Scenario 1 and Scenario 2 on src host:
{"execute":"calc-dirty-rate", "arguments": {"calc-time": 3}}
{"return": {}}
{"execute":"query-dirty-rate"}
{"return": {"status": "measured", "dirty-rate": 61, "start-time": 218710, "calc-time": 3}}
{"execute":"calc-dirty-rate", "arguments": {"calc-time": 3}}
{"return": {}}
{"execute":"query-dirty-rate"}
{"return": {"status": "measured", "dirty-rate": 58, "start-time": 219020, "calc-time": 3}}
{"execute":"calc-dirty-rate", "arguments": {"calc-time": 1}}
{"return": {}}
{"execute":"query-dirty-rate"}
{"return": {"status": "measured", "dirty-rate": 204, "start-time": 219044, "calc-time": 1}}
{"execute":"calc-dirty-rate", "arguments": {"calc-time": 1}}
{"return": {}}
{"execute":"query-dirty-rate"}
{"return": {"status": "measured", "dirty-rate": 196, "start-time": 219068, "calc-time": 1}}
{"execute":"calc-dirty-rate", "arguments": {"calc-time": 3}}
{"return": {}}
{"execute":"query-dirty-rate"}
{"return": {"status": "measured", "dirty-rate": 60, "start-time": 219082, "calc-time": 3}}
{"execute":"calc-dirty-rate", "arguments": {"calc-time": 1}}
{"return": {}}
{"execute":"query-dirty-rate"}
Notes: have checked the stressapptest program, it works well.
Expected results:
The dirty-rate shouldn't be divided by calc-time.
Additional info:
https://bugzilla.redhat.com/show_bug.cgi?id=1833235#c14
Comment 1Dr. David Alan Gilbert
2021-01-25 12:51:33 UTC
This maybe a limitation of the mechanism used; It works by doing:
a) Start dirty tracking
b) Wait for calc-time
c) Stop dirty tracking
d) Count number of pages dirty
That can't tell the difference between a large area of memory that's slowly changed during 'calc-time'
and the same area of memory that's rapidly changed repeatedly.
Using the 1 second calc-time seems to make more sense here; any scaling seems bogus.
An interesting question is whether we could provide the user with the results
with different calc-time's - that could then distinguish between the two cases.
Move RHEL-AV bugs to RHEL9. If necessary to resolve in RHEL8, then clone to the current RHEL8 release.
Comment 8RHEL Program Management
2022-07-25 07:28:06 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.
Description of problem: dirty-rate is divided by calc-time when calculate guest dirty-rate Version-Release number of selected component (if applicable): host info: kernel-4.18.0-275.el8.x86_64&qemu-kvm-5.2.0-3.module+el8.4.0+9499+42e58f08.x86_64 guest info: kernel-4.18.0-275.el8.x86_64 How reproducible: 100% Steps to Reproduce: 1.Boot a guest on src host, please see qemu command[1]; 2.Run stress in guest # stressapptest -M 200 -s 100000 3.Query dirty rate via qmp cmds (1)Scenario 1: set calc-time to 3: {"execute":"calc-dirty-rate", "arguments": {"calc-time": 3}} (2)Scenario 2: set calc-time to 1: {"execute":"calc-dirty-rate", "arguments": {"calc-time": 1}} after (1) or (2), check dirty rate: {"execute":"query-dirty-rate"} Actual results: After step 3, get different dirty rate between Scenario 1 and Scenario 2 on src host: {"execute":"calc-dirty-rate", "arguments": {"calc-time": 3}} {"return": {}} {"execute":"query-dirty-rate"} {"return": {"status": "measured", "dirty-rate": 61, "start-time": 218710, "calc-time": 3}} {"execute":"calc-dirty-rate", "arguments": {"calc-time": 3}} {"return": {}} {"execute":"query-dirty-rate"} {"return": {"status": "measured", "dirty-rate": 58, "start-time": 219020, "calc-time": 3}} {"execute":"calc-dirty-rate", "arguments": {"calc-time": 1}} {"return": {}} {"execute":"query-dirty-rate"} {"return": {"status": "measured", "dirty-rate": 204, "start-time": 219044, "calc-time": 1}} {"execute":"calc-dirty-rate", "arguments": {"calc-time": 1}} {"return": {}} {"execute":"query-dirty-rate"} {"return": {"status": "measured", "dirty-rate": 196, "start-time": 219068, "calc-time": 1}} {"execute":"calc-dirty-rate", "arguments": {"calc-time": 3}} {"return": {}} {"execute":"query-dirty-rate"} {"return": {"status": "measured", "dirty-rate": 60, "start-time": 219082, "calc-time": 3}} {"execute":"calc-dirty-rate", "arguments": {"calc-time": 1}} {"return": {}} {"execute":"query-dirty-rate"} Notes: have checked the stressapptest program, it works well. Expected results: The dirty-rate shouldn't be divided by calc-time. Additional info: https://bugzilla.redhat.com/show_bug.cgi?id=1833235#c14