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.
Bug 1247688 - iops_max and iops can not work as expected
Summary: iops_max and iops can not work as expected
Keywords:
Status: CLOSED NOTABUG
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: qemu-kvm
Version: 7.1
Hardware: All
OS: Linux
medium
high
Target Milestone: rc
: ---
Assignee: Stefan Hajnoczi
QA Contact: Virtualization Bugs
URL:
Whiteboard:
Depends On: 1150403
Blocks: 1146755 1247830
TreeView+ depends on / blocked
 
Reported: 2015-07-28 15:36 UTC by Ademar Reis
Modified: 2015-07-29 13:55 UTC (History)
11 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of: 1150403
Environment:
Last Closed: 2015-07-29 13:55:39 UTC
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)

Description Ademar Reis 2015-07-28 15:36:54 UTC 
Clonning from -rhev package, as I/O throttling appears to be enabled in the vanilla qemu-kvm package as well in RHEL7.

+++ This bug was initially created as a clone of Bug #1150403 +++

Description of problem:
When boot guest with "iops_max=10000,iops=100", throttling can not be triggered once "I/O pool" is empty.

Version-Release number of selected component (if applicable):
qemu-kvm-rhev-2.1.0-5.el7.x86_64

How reproducible:
100%

Steps to Reproduce:
1.boot guest with following cli:
# /usr/libexec/qemu-kvm -M pc -m 2G -smp 2 -spice port=5931,disable-ticketing -monitor stdio -qmp tcp::8888,server,nowait \
-drive file=/home/RHEL-Server-7.0-64-virtio.qcow2,if=none,id=img,snapshot=on,bps_max=1024000000 \
-device virtio-blk-pci,drive=img,id=sys-img \
-netdev tap,id=tap0,script=/etc/qemu-ifup \
-device virtio-net-pci,netdev=tap0,id=net0,mac=24:be:05:11:15:11 \
-drive file=/home/data.qcow2,if=none,id=disk0,iops_max=10000,iops=100,cache=none \
-device virtio-blk-pci,drive=disk0,id=sys-disk0
2.do testing inside guest using fio.
# fio --filename=/dev/vdb --direct=1 --rw=randwrite --bs=64k --size=1000M --name=test --iodepth=1 --ioengine=libaio --runtime=60s
3.repeat step 2 after step 2 finished.

Actual results:
###After step 2, got results as followings:
...
  write: io=994.77MB, bw=16976KB/s, iops=265, runt= 60005msec
...
Here: 265*60 > 10000.

###After step 3, got following results:
...
  write: io=567040KB, bw=9450.4KB/s, iops=147, runt= 60002msec
...

Expected results:
After step 3, should got the value of iops <= 100. Not "iops=147". 

Additional info:

--- Additional comment from Gu Nini on 2015-03-12 04:56:02 BRT ---

The bug also occurred under power KVM, the detailed software versions are as follows:

Host kernel: 3.10.0-229.el7.ppc64
Qemu KVM: 
qemu-kvm-common-rhev-2.2.0-5.el7.ppc64
qemu-kvm-tools-rhev-2.2.0-5.el7.ppc64
qemu-img-rhev-2.2.0-5.el7.ppc64
qemu-kvm-rhev-2.2.0-5.el7.ppc64
qemu-kvm-rhev-debuginfo-2.2.0-5.el7.ppc64

That's the combined options iops and iops_max, bps and bps_max, iops_rd and iops_rd_max, iops_wr and iops_wr_max, bps_rd and bps_rd_max, bps_wr and bps_wr_max, could not work as expected as that in the bug.

Also change the 'Hardware' field to 'All' since it exists on both x86_64 and ppc64.
Comment 2 Stefan Hajnoczi 2015-07-29 13:55:39 UTC 
RHEL7 qemu-kvm has an older I/O throttling implementation which does not support the "bps_max" parameter.  This bug does not apply.
Note You need to log in before you can comment on or make changes to this bug.