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Transmit performance is poor on NetXen's P3 based 10GB NICs (1021940)

Details

By default, the hardware feature for checksum offloading is disabled for NetXen's P3 based NIC devices in ESX 4.0 Update 1. Since TCP segmentation offloading and large segment offloading (TSO/LSO) are also disabled when checksum offloading is disabled, it results in reduced transmit performance of P3 based 10GB NICs.

Solution

This issue is resolved in ESX/ESXi 4.0 Update 2. For more information, see VMware ESX 4.0, Patch ESX400-201006211-UG: Updates the VMware ESX 4.0 nx-nic device driver (1017731).
 
To work around this issue:
  1. Load the nx_nic driver using the module parameter force_hw_ipcsum to enable or disable hardware checksum offloading: 
    • To enable hardware checksum offloading for P2/P3 based cards, run this command:

      #esxcfg-module -s "force_hw_ipcsum=1" nx_nic

    • To disable hardware checksum offload for P2/P3 based cards, run this command:

      #esxcfg-module -s "force_hw_ipcsum=0" nx_nic

    • To enable hardware checksum offload for P2 based cards only (default setting), run this command:

      #esxcfg-module -s "force_hw_ipcsum=-1" nx_nic

    • To set the parameters to default, run this command:

      #esxcfg-module -s " " nx_nic

  2. Reboot the ESX host so the changes are updated in esx.conf file:

    #esxcfg-boot -b 
Note: The best practice is to disable hardware checksum offloading for P3 based Quad Port 1GB NICs.

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