Bug 1265205

patch merged upstream -> MODIFIED

moving back to MODIFIED. Patch 47013 fixes tests only, production code works OK.

I want MODIFIED!
Bot, please leave me alone...:-)

Looks like the code fix made it in, to vdsm-4.16.29-1.el7ev.x86_64, 
but the new vdsm configuration is not part of the default settings of vdsm.conf

To enable this feature we had to manually set ""cpu_affinity = 1"

The default settings on a new system are:

# rpm -qa|grep vdsm
vdsm-xmlrpc-4.16.29-1.el7ev.noarch
vdsm-yajsonrpc-4.16.29-1.el7ev.noarch
vdsm-cli-4.16.29-1.el7ev.noarch
vdsm-4.16.29-1.el7ev.x86_64
vdsm-python-zombiereaper-4.16.29-1.el7ev.noarch
vdsm-python-4.16.29-1.el7ev.noarch
vdsm-hook-ethtool-options-4.16.29-1.el7ev.noarch
vdsm-jsonrpc-4.16.29-1.el7ev.noarch

# cat vdsm.conf
[vars]
ssl = true

[addresses]
management_port = 54321

Francesco/Michal, Should we respin to enable it by default?

(In reply to Gil Klein from comment #5)
> Looks like the code fix made it in, to vdsm-4.16.29-1.el7ev.x86_64, 
> but the new vdsm configuration is not part of the default settings of
> vdsm.conf
> 
> To enable this feature we had to manually set ""cpu_affinity = 1"
[...] 

> # cat vdsm.conf
> [vars]
> ssl = true
> 
> [addresses]
> management_port = 54321
> 
> Francesco/Michal, Should we respin to enable it by default?

Please note that for 3.5, having it disabled by default was intentional (at least in my intentions :) ) because we are pretty deep in maintenance mode for 3.5.x series, so, despite the benefits we observed, this seemed like a too invasive change.

Furthermore, to enable it is very easy.

For 3.6.x and further we are discussing if enabling it by default on
https://bugzilla.redhat.com/show_bug.cgi?id=1279431

restoring NEEDINFO on Michal as per comment 5.

(In reply to Gil Klein from comment #5)
> Looks like the code fix made it in, to vdsm-4.16.29-1.el7ev.x86_64, 
> but the new vdsm configuration is not part of the default settings

Intentionally

 Francesco/Michal, Should we respin to enable it by default?

We'd love to get more feedback before that. It is tracked in bug 1279431

(In reply to Michal Skrivanek from comment #8)
> (In reply to Gil Klein from comment #5)
> > Looks like the code fix made it in, to vdsm-4.16.29-1.el7ev.x86_64, 
> > but the new vdsm configuration is not part of the default settings
> 
> Intentionally
> 
>  Francesco/Michal, Should we respin to enable it by default?
> 
> We'd love to get more feedback before that. It is tracked in bug 1279431
Make sense. How do we make sure it is documented?

If this bug requires doc text for errata release, please provide draft text in the doc text field in the following format:

Cause:
Consequence:
Fix:
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Update from scale:

Initial checks show cpu_affinity correctly limits vdsm utilization to 1 core.
Preparing VDSM regression workloads w/and without CPU_Affinity to verify VDSM behavior; will update relevant stakeholders afterward.

hi Francesco,
     I have updated the doc text. Please let me know if you have any feedback. 
Also, I don't think we tell users to edit the vdsm.conf file for other options so I'm a bit confused if this feature should be added to the main docs suite. Including Andrew and Yaniv. Do we need a docs bug for this?

Cheers,
Julie

(In reply to Julie from comment #12)
> hi Francesco,
>      I have updated the doc text. Please let me know if you have any
> feedback. 
> Also, I don't think we tell users to edit the vdsm.conf file for other
> options so I'm a bit confused if this feature should be added to the main
> docs suite. Including Andrew and Yaniv. Do we need a docs bug for this?
> 
> Cheers,
> Julie


Hi Julie. The doc text seems fine.
I think the user should be aware of this option, which may have a rather big impact on the node running VDSM.

However, I don't know the best way to convey this information, so I can't really help here.

Hi Yaniv, 
   Please see #comment12.

Cheers,
Julie

(In reply to Julie from comment #15)
> Hi Yaniv, 
>    Please see #comment12.
> 
> Cheers,
> Julie

I think a kbase on tuning this in scale machine is the best way to document this since we do not have a tuning guide.

Scale re-run complete, updated info at docs/DOC-1055603

Showed:
Reduced VDSM Process CPU Utilization when CPU Affinity is set to 1.
Improved transactional throughput & http response time for VDSM workload.

QEMU-KVM utilization unrelated; caused by rate of VM start up.
Moving to verified.

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://rhn.redhat.com/errata/RHBA-2015-2530.html