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A Method to Reduce PCI Read Transactions Generated by PCI NIC Drivers

IP.com Disclosure Number: IPCOM000008436D
Publication Date: 2002-Jun-13
Document File: 2 page(s) / 110K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for tuning a PCI network adapter device driver so that it greatly reduces the number of reads generated on the PCI bus. Benefits include a throughput that can be constantly and accurately monitored.

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A Method to Reduce PCI Read Transactions Generated by PCI NIC Drivers

Disclosed is a method for tuning a PCI network adapter device driver so that it greatly reduces the number of reads generated on the PCI bus. Benefits include a throughput that can be constantly and accurately monitored.

Background

Most PCI network adapters have on-board statistic counter registers that keep track of the number of packets transmitted and received. The registers also keep track of other useful statistics, such as number of dropped frames and bad packet checksums. These registers are typically accessed by issuing a single PCI read transaction for each register that is read. If a network adapter’s device driver wants to effectively monitor the network traffic that goes in and out of the network adapter, it must constantly poll these registers on the PCI network adapter. 

Note. Constant monitoring is extremely useful if the network adapter’s device driver is “self-healing” or “self-tuning.” This type of driver adjusts performance based on the transmit and receive performance of the network adapter and/or the device driver.

Newer and more advanced PCI network adapters have dozens of on-board statistic counter registers that must be read by the device driver in order to collect statistics. This can cause hundreds of PCI read transactions to occur, which degrades the performance of the network adapter. Performance is degraded because the network adapter attempts to send and receive network traffic via the PCI bus at the same time that PCI read transactions are happening. At this point, the PCI bus is literally flooded w...