Bug 1592990

Summary:	Cannot set number of IO threads via the UI
Product:	[oVirt] ovirt-engine	Reporter:	Sigbjorn Lie <sigbjorn>
Component:	Frontend.WebAdmin	Assignee:	Andrej Krejcir <akrejcir>
Status:	CLOSED CURRENTRELEASE	QA Contact:	meital avital <mavital>
Severity:	medium	Docs Contact:
Priority:	unspecified
Version:	4.2.3	CC:	abpatil, bugs, gianluca.cecchi, mavital, michal.skrivanek, rbarry
Target Milestone:	ovirt-4.2.8	Keywords:	Reopened, ZStream
Target Release:	---	Flags:	rule-engine: ovirt-4.2+
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:	ovirt-engine-4.2.8.1	Doc Type:	Enhancement
Doc Text:	Feature: The number of IO threads can be set in the web UI in the new/edit VM dialog. Reason: Some users may need to set the number of IO threads and using web UI can be easier than REST API.	Story Points:	---
Clone Of:
Clones:	1594216 1651255 (view as bug list)		Environment:
Last Closed:	2019-01-22 10:23:01 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	Virt	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	1594216, 1651255

Description Sigbjorn Lie 2018-06-19 19:35:50 UTC

Description of problem:
In rhev/oVirt 4.1 there was possible to enable I/O threads for a VM and then there was a field to define how many I/O threads.

In 4.2 this option is gone. 

We've had good performance gains when adding more than 1 IO thread for IO intensive vms, such as Katello/Satellite 6. 

Using the API to set nr of IO threads is cumbersome. Please add the option for selecting amount of IO threads back to the webui.

Version-Release number of selected component (if applicable):
4.2

How reproducible:
every time

Steps to Reproduce:
1.
2.
3.

Actual results:


Expected results:


Additional info:

Comment 1 Gianluca Cecchi 2018-06-20 11:36:18 UTC

To be noted that as it is now (not possible to specify inside the GUI the number of I/O threads), in my opinion the documentation is a bit misleading here:
https://access.redhat.com/documentation/en-us/red_hat_virtualization/4.2/html/virtual_machine_management_guide/editing_io_threads
Reading the guide, it gave me the idea that it is possible to change the number, even if the default and recommended (upon which kinds of tested scenarios?) one is to leave the value of "1"

Comment 5 Gianluca Cecchi 2018-06-21 15:24:10 UTC

why?

Comment 6 Sigbjorn Lie 2018-06-21 17:26:06 UTC

Yes please explain why you so arrogantly closed the request without even an explanation why.

Comment 7 Michal Skrivanek 2018-06-22 11:57:30 UTC

It makes the UI simpler, and ensure people don't set it to ridiculous values. 
In most cases apparently a single IO thread is enough.
For exceptional cases where more are beneficial there's REST API.

If you believe you have a good widespread example of VM/workload where more have sense then please share that. Also patches are welcome, of course, if you can keep the UI simple to use.

Comment 8 Michal Skrivanek 2018-06-22 12:01:32 UTC

(In reply to Gianluca Cecchi from comment #1)
> To be noted that as it is now (not possible to specify inside the GUI the
> number of I/O threads), in my opinion the documentation is a bit misleading

thanks! cloned to a doc bug

Comment 9 Gianluca Cecchi 2018-06-22 14:18:16 UTC

I can try to re-setup a test env using Oracle RDBMS and HammerDB as stresstest utility, showing you performance number changes.
But I remember that when having 3 data virtual disks to store Oracle datafiles, it gave a performance gain between 10% and 15% in I/O performances, assigning 1 I/O thread for every virtual disk during the TPC-C environment creation, using 20 concurrent virtual users to create 200 stores of the tpcc db user.

I think that a clear tool-tip and a warning about the improper use of the setting would be sufficient.
I think also that typically the webadmin gui will be used by a supposed expert admin guy with seniority level.
Eventually you can setup so that the parameter is editable only by a user with sort of particular admin rights, but it is not desirable to "penalize" the others forcing them to use REST/API for this.
Just my 2 eurocent ;-)

Comment 10 Gianluca Cecchi 2018-06-22 14:19:10 UTC

Also, you could put a constraint so that you don't allow to set a number that is > of the total number of virtual disks of the VM

Comment 11 Sigbjorn Lie 2018-06-28 11:12:20 UTC

I agree that a tooltip and warning would be sufficient as the webadmin gui is supposed to be used by expert admin guys and not novice end users.

We've seen the storage io wait time to down when increasing the amount of io threads for a vm with several disks and lots of io. 

Satellite 6 is an example, using 2 different databases and a lot of file system activity going on the same time. We seperate databases from filsystems in different LVM volume groups on different disks assigned to the Satellite VM. Adding more than 1 io thread was required to bring the iowait down, going from double digit % iowait to the current 0.14% iowait.

This has proven to be true for other disk intensive workloads as well.

Please bring back the ability to specify the amount of io threads in the webadmin ui. 

Thanks.

Comment 12 Michal Skrivanek 2018-08-13 07:27:15 UTC

I guess you can take 5eb925f50c39 and partially revert that, with a different UI part. Or make it a predefined property instead.

Comment 16 meital avital 2018-10-28 15:09:23 UTC

Verified:
vdsm-4.30.1-25.gitce9e416.el7.x86_64
ovirt-engine-4.3.0-0.0.master.20181023141116.gitc92ccb5.el7.noarch

Comment 18 Raz Tamir 2018-11-28 15:30:56 UTC

QE verification bot: the bug was verified upstream

Comment 19 Sandro Bonazzola 2019-01-22 10:23:01 UTC

This bugzilla is included in oVirt 4.2.8 release, published on January 22nd 2019.

Since the problem described in this bug report should be
resolved in oVirt 4.2.8 release, it has been closed with a resolution of CURRENT RELEASE.

If the solution does not work for you, please open a new bug report.