[CentOS-virt] What kernel params to use with KVM hosts??

Wed Mar 17 05:18:11 UTC 2010
Steven Ellis <steven.ellis at bulletin.net>

carlopmart wrote:
> Hi all,
>
>   I order to reach maximum performance on my centos kvm hosts I have use these params:
>
>   - On /etc/grub.conf:
>
>     kernel /vmlinuz-2.6.18-164.11.1.el5 ro root=LABEL=/ elevator=deadline quiet
>
>   - On sysctl.conf
>
>    # Special network params
>    net.core.rmem_default = 8388608
>    net.core.wmem_default = 8388608
>    net.core.rmem_max = 16777216
>    net.core.wmem_max = 16777216
>    net.ipv4.tcp_rmem = 1048576 4194304 16777216
>    net.ipv4.tcp_wmem = 1048576 4194304 16777216
>
>
>    # Disable netfilter on bridges.
>    net.bridge.bridge-nf-call-ip6tables = 0
>    net.bridge.bridge-nf-call-iptables = 0
>    net.bridge.bridge-nf-call-arptables = 0
>
>    # Virtual machines special kernel params
>    vm.swappiness = 0
>   
Care to explain some of your choices.

In particular why

vm.swappiness = 0

and why elevator=deadline over noop.

Steve

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