How To Bypass Local Cache (Disable tx-nocache-copy)

 

"tx-nocache-copy" is a feature which bypasses local cache and writes user-space data directly into memory. 

New kernels have this feature disabled by default, while on it comes enabled on some Linux distributions.

It is recommended to disable this feature, as it can harm performance.

 

References

• Ethtool Commands

 

Configuration

To disable tx-nocache-copy, run:

# ethtool -K eth1 tx-nocache-copy off

To enable tx-nocache-copy, run:

# ethtool -K eth1 tx-nocache-copy on

To view current configuration, run:

# ethtool --show-offload eth1 | grep tx-nocache-copy

tx-nocache-copy: off

译者注:

1. tx-nocache-copy 这个网卡参数是rhel7.x才有的参数,rhel6.x没有这个网卡参数.

2. 该参数在rhel7.3中是默认禁用的:　

[root@rhel73 ~]# uname -r
3.10.0-514.el7.x86_64
[root@rhel73 ~]# ethtool --show-offload  ens33 | grep tx-nocache-copy
tx-nocache-copy: off
[root@rhel73 ~]# cat /etc/redhat-release 
Red Hat Enterprise Linux Server release 7.3 (Maipo)
[root@rhel73 ~]#