Mtrr Mapping and Write Combining

C – Troubleshooting BIOS Settings

C.2.1

MTRR (Memory Type Range Registers) is used by the InfiniPath driver to enable write combining to the InfiniPath on-chip transmit buffers. This improves write bandwidth to the InfiniPath chip by writing multiple words in a single bus transaction (typically 64). This applies only to x86_64 systems. To see if is working correctly and to check your bandwidth use this command:

$ ipath_pkt_test -B

When configured correctly, PCIe InfiniPath will normally report in the range of 1150-1500 MB/s, while HTX InfiniPath cards will normally report in the range of 2300-2650 MB/s.

However, some BIOSes don’t have the MTRR mapping option. It may be referred to in a different way, dependent upon chipset, vendor, BIOS, or other factors. For example, it is sometimes referred to as "32 bit memory hole", which should be enabled.

If there is no setting for MTRR mapping or 32 bit memory hole, please contact your system or motherboard vendor and inquire as to how write combining may be enabled.

C.2.2

Incorrect MTRR Mapping

In some cases, the InfiniPath driver may be unable to configure the CPU Write Combining attributes for the QLogic InfiniPath IBA6110. This would normally be seen for a new system, or after the system’s BIOS has been upgraded or reconfigured.

If this error occurs, the InfiniPath interconnect will operate, but in a degraded performance mode. Typically the latency will increase to several microseconds, and the bandwidth may decrease to as little as 200 MBytes/sec.

A message similar to this will be printed on the console, and normally to the system log (typically in /var/log/messages):

infinipath: mtrr_add(feb00000,0x100000,WC,0) failed (-22)

infinipath: probe of 0000:04:01.0 failed with error -22

If you see this error message, you should edit the BIOS setting for MTRR Mapping. The setting should look like this:

MTRR Mapping

[Discrete]

You can check and adjust the BIOS settings using the BIOS Setup Utility. Check the hardware documentation that came with your system for more information on how to do this. Section C.2.3, below, documents a related issue.

IB6054601-00 D

C-3

IB6054601-00 D specifications

The Q-Logic IB6054601-00 D is a high-performance InfiniBand adapter card designed for data centers and enterprise applications requiring robust connectivity and low-latency communication. This adapter is part of QLogic's extensive portfolio of networking solutions, catering to the needs of high-performance computing (HPC), cloud computing, and virtualization environments.

One of the standout features of the IB6054601-00 D is its capability to support data transfer rates of up to 56 Gbps. This makes it ideal for applications demanding large bandwidth and quick data processing. The adapter is optimized for RDMA (Remote Direct Memory Access) technology, which allows data to be transferred directly between the memory of different computers without involving the CPU. This reduces latency and CPU overhead, leading to enhanced overall system performance.

The architecture of the IB6054601-00 D includes support for a dual-port design, which offers increased bandwidth, redundancy, and fault tolerance. This dual-port configuration is especially advantageous for environments that require high availability and reliability, such as financial services and mission-critical applications.

The adapter utilizes advanced error detection and correction mechanisms, ensuring that data integrity is maintained during transmission. With features like adaptive routing and congestion management, the IB6054601-00 D is capable of optimizing the handling of data flows, thereby enhancing performance even under heavy loads.

In terms of compatibility, the Q-Logic IB6054601-00 D supports a wide range of operating systems and virtualization technologies, making it easy to integrate into diverse IT environments. It also includes drivers and software packages that facilitate seamless deployment and management.

In addition to high-speed connectivity, the adapter is designed with power efficiency in mind. It adheres to Energy Star regulations, helping organizations lower their operational costs while minimizing their environmental footprint.

Overall, the Q-Logic IB6054601-00 D stands out for its high throughput, low latency, and reliability. Its combination of advanced features and technologies positions it as an excellent choice for organizations looking to enhance their data center performance and maximize the efficiency of their network infrastructure. With the growing demands for faster and more efficient data transfer, solutions like the IB6054601-00 D are essential in meeting the evolving needs of modern enterprises.

Q-Logic IB6054601-00 D manual Mtrr Mapping and Write Combining, Incorrect Mtrr Mapping

Models: IB6054601-00 D