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yael
Asked: 2016-03-10 08:10:37 +0800 CST

Redhat 7.1 - increase NIC ring buffer

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My target is to increase the ring buffer ( I have Linux red-hat 7.1 ) , but I get the following:

ethtool -G eth1 rx 8192
Cannot set device ring parameters: Invalid argument

so how to enable this value? , or maybe this is the MAX value?

the current status:

ethtool -g eth1
Ring parameters for eth1:
Pre-set maximums:
RX:             4096
RX Mini:        0
RX Jumbo:       0
TX:             4096
Current hardware settings:
RX:             256
RX Mini:        0
RX Jumbo:       0
TX:             512

Remark - I want to increase the ring buffer because errors - pkts rx OOB - indicate that the network card is out of buffer

# ethtool -i eth1
  driver: vmxnet3
  version: 1.1.30.0-k-NAPI
  firmware-version:
  bus-info: 0000:1b:00.0
  supports-statistics: yes
  supports-test: no
  supports-eeprom-access: no
  supports-register-dump: yes
  supports-priv-flags: no


  more /etc/modprobe.d/blacklist.conf
  blacklist ipv6


  more /etc/sysconfig/network-scripts/ifcfg-eth1

  MTU=9000
  DEVICE=eth1
  HWADDR=70:10:76:9E:02:81
  TYPE=Ethernet
  ONBOOT=yes
  BOOTPROTO=static
  NETMASK=255.255.255.0
  IPADDR=12.160.0.36


  modinfo vmxnet3
  filename:       /lib/modules/3.10.0-    229.14.1.el7.x86_64/kernel/drivers/net/vmxnet3/vmxnet3.ko
  version:        1.1.30.0-k
  license:        GPL v2
  description:    VMware vmxnet3 virtual NIC driver
  author:         VMware, Inc.
  rhelversion:    7.1
  srcversion:     EF80BF71B6F577C3370F410
  alias:          pci:v000015ADd000007B0sv*sd*bc*sc*i*
  depends:
  intree:         Y
  vermagic:       3.10.0-229.14.1.el7.x86_64 SMP mod_unload modversions
  signer:         Red Hat Enterprise Linux kernel signing key
  sig_key:         44:02:00:8F:2B:3F:DA:1F:6C:1C:64:BA:2C:10:BF:0C:FE:EC:AB:B7
  sig_hashalgo:   sha256
linux

2 Answers

  1. Increasing Ring Buffers Beyond Driver Default Limits

    You are trying to set RX to 8192, but the driver default limits are 4096 as per your output.

    To increase the limits imposed by the driver, you will need to first see what driver you are using ethtool -i eth1 and use modinfo vmxnet3 in your case, or the driver documentation to get the options available for that driver.

    You would then set the options as desired and as supported by the driver in a custom file /etc/modprobe.d/drivername.conf

    You could either unload and reinstall the driver manually, or reboot for the settings to take effect.

    Disclaimer: If you choose a setting that the driver does not properly support, you will lose network connectivity and will have to restore the configuration from a console or out-of-band console device such as iLo or iDrac or other remote management interface. I am providing this disclaimer for anyone doing this on bare metal. In this example, they are using VMWare, so they could use the vSphere console to regain access and restore settings.

    • 3

  2. Your maximum value is 4096, as per the ethtool output.

    Please try that value.

    The maximum value varies depending on your hardware. For instance:

    [root@LAS ~]# ethtool -g eth1
Ring parameters for eth1:
Pre-set maximums:
RX:     2047
RX Mini:    0
RX Jumbo:   0
TX:     511
Current hardware settings:
RX:     200
RX Mini:    0
RX Jumbo:   0
TX:     511
    • 1