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New Kernel for CloudLinux 5.x: 2.6.18-374.3.1.el5.lve0.8.44

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Igor Seletskiy
10/10/201100:0310/10/2011 00:03:36
New kernel 2.6.18-374.3.1.el5.lve0.8.44 is available. It includes following bug fixes and new features:
  • Rebased to upstream kernel 028stab094.3 including security and bug fixes RHSA-2011:1212
  • Kernel panic fix for lve_list_next race condition
  • Rebase to upstream 28stab093.2 kernel (security and bug fixes RHSA-2011:1065)
  • Ability to change NCPU on the fly
  • Ability to destroy LVE on the fly (via API)
  • Two modes to calculate load averages with ability to switch between them
  • Fix for OOM/hanged task issue
  • IO Priorities
Code
# yum install kernel

If you have PAE, xen or Enterprise kernel -- use corresponding prefix, like: kernel-PAE, kernel-xen, kernel-ent instead of kernel

To change NCPU on the fly, use:
Code
# lvectl set LVE_ID --ncpu N --force
--force will cause NCPU change on the fly. Please, don't use that option with kernels prior to lve0.8.42, as it can crash the system

Load Averages
CloudLinux has a  modified way to calculated load averages, as processes can wait on CPU because of LVE limits, and not because of lack of CPU resources. Previously, our LA algorithm was ignoring uninterruptable processes. You can now switch to another LA algorithm that accounts for uninterruptable processes by running:
Code
sysctl -w kernel.full_loadavg=1


Switching to that mode will cause higher load averages during high IO activity intervals. This should be useful on cPanel servers that have high IO Wait without high load average

You can always switch back by running:
Code
sysctl -w kernel.full_loadavg=0
IO Priorities

While we still planning to release IO limits by the end of this year, this release introduces IO priorities. Each LVE is set to have IO priority of 100 by default (highest possible).
You can lower that priority, causing particular LVE to be de-prioritizes IO wise. This means that if there is lack of resources on the server, that LVE will get less IO operations then other LVEs.
IO Priorities work only with CFQ IO scheduler.



Igor Seletskiy
10/10/201100:0310/10/2011 00:03:36
Views:2039 Comments:5 0
Tags: kernel, lve, ncpu
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kernow
10/10/2011 08:16:43
When will this new kernel be available?
#Package kernel-2.6.18-338.19.1.el5.lve0.8.36.x86_64 already installed and latest version
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Igor Seletskiy
10/10/2011 08:18:58
It should be in available now. Please, try doing: # yum clean all
and then:
# yum update kernel
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kernow
10/10/2011 08:25:25
#yum clean all worked, thanks.
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David Majchrzak
10/14/2011 04:57:20
fs.proc_super_gid
Did this make it into the stable kernel?
Quote
fs.proc_super_gid was added to specify group of users that can see all processes
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Igor Seletskiy
10/14/2011 08:27:15
Yes, sure. It is in this lve0.8.44 kernel
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