Bug 770123

Summary: Remove max_cstate=1 from the oVirt Node kernel command line default options
Product: Red Hat Enterprise Linux 6 Reporter: Perry Myers <pmyers>
Component: ovirt-nodeAssignee: Mike Burns <mburns>
Status: CLOSED ERRATA QA Contact: Virtualization Bugs <virt-bugs>
Severity: medium Docs Contact:
Priority: medium    
Version: 6.2CC: acathrow, bsarathy, cshao, gouyang, jboggs, leiwang, mburns, ovirt-bugs, ovirt-maint, sgordon, tburke, ycui
Target Milestone: rc   
Target Release: ---   
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: ovirt-node-2.2.3-1.el6 Doc Type: Bug Fix
Doc Text:
Previously the Hypervisor always included 'max_cstate=1' in the kernel boot options. This limited the cstates available to the processor, avoiding clock skew on older hardware. The Hypervisor has been updated and this option is now only used on older hardware where clock skew issues are anticipated. On newer hardware where this is not an issue all supported cstates are available.
 Story Points: ---
Clone Of: 770122
: 770153 (view as bug list) Environment:
Last Closed: 2012-07-19 14:17:22 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Bug Depends On: 770122    
Bug Blocks: 770153    

Description Perry Myers 2011-12-23 13:19:44 UTC 
+++ This bug was initially created as a clone of Bug #770122 +++

Description of problem:
max_cstate=1 was added to kernel defaults for oVirt Node due to a large portion of hardware having issues w/ time sync in kvm.

As long as hardware has a stable/constant tsc, it should be safe to remove this restriction.  People with older hardware can always manually add it back in.
Comment 6 Stephen Gordon 2012-03-30 19:10:21 UTC 
    Technical note added. If any revisions are required, please edit the "Technical Notes" field
    accordingly. All revisions will be proofread by the Engineering Content Services team.
    
    New Contents:
Previously the Hypervisor always included 'max_cstate=1' in the kernel boot options. This limited the cstates available to the processor to limit clock skew on older hardware. The Hypervisor has been updated and this option is now only used on hardware where clock skew issues are anticipated.
Comment 7 Stephen Gordon 2012-03-30 19:15:50 UTC 
    Technical note updated. If any revisions are required, please edit the "Technical Notes" field
    accordingly. All revisions will be proofread by the Engineering Content Services team.
    
    Diffed Contents:
@@ -1 +1 @@
-Previously the Hypervisor always included 'max_cstate=1' in the kernel boot options. This limited the cstates available to the processor to limit clock skew on older hardware. The Hypervisor has been updated and this option is now only used on hardware where clock skew issues are anticipated.+Previously the Hypervisor always included 'max_cstate=1' in the kernel boot options. This limited the cstates available to the processor, avoiding clock skew on older hardware. The Hypervisor has been updated and this option is now only used on hardware where clock skew issues are anticipated.
Comment 8 Stephen Gordon 2012-03-30 19:17:49 UTC 
    Technical note updated. If any revisions are required, please edit the "Technical Notes" field
    accordingly. All revisions will be proofread by the Engineering Content Services team.
    
    Diffed Contents:
@@ -1 +1 @@
-Previously the Hypervisor always included 'max_cstate=1' in the kernel boot options. This limited the cstates available to the processor, avoiding clock skew on older hardware. The Hypervisor has been updated and this option is now only used on hardware where clock skew issues are anticipated.+Previously the Hypervisor always included 'max_cstate=1' in the kernel boot options. This limited the cstates available to the processor, avoiding clock skew on older hardware. The Hypervisor has been updated and this option is now only used on older hardware where clock skew issues are anticipated. On newer hardware where this is not an issue all supported cstates are available.
Comment 12 errata-xmlrpc 2012-07-19 14:17:22 UTC 
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.

http://rhn.redhat.com/errata/RHBA-2012-0741.html