Memory

Memory channels

Obtaining the correct number of memory channels (the -n argument) is tricky because it depends on how many channels the system board supports, the number and types of memory chips and how they are physically installed in the system and there’s no easy or even reliable way to tell from a running system.

This info should be available during bootup in the BIOS memory check stage, during runtime dmidecode can help in making at least an educated guess.

Unless its already installed, you’ll need to do so now:

# yum install dmidecode

This usually gives sufficient amount of information to look up the system and/or motherboard manuals to see what the board supports and in which configurations, memory slot population is critical to multi-channel support:

# dmidecode -t system
# dmidecode -t baseboard

This outputs the populated memory slots on the system:

# dmidecode -t memory | grep 'Size: [0-9]'

If there’s just one, it cannot be using multichannel memory. If there are two or its multiple, it might be dual-channel, if there are three or its multiple it might be triple-channel, if there are four or its multiple it might be quad-channel. Or dual-channel…

In addition there could be further hints in the Locator fields of the memory devices, such as ChannelA-DIMM0 and ChannelB-DIMM0:

# dmidecode -t memory | grep Locator: