Using dmidecode to determine physical RAM and processors - Revision history

Hutch at 03:49, 16 December 2008

Hutch — Tue, 16 Dec 2008 03:49:23 GMT

←Older revision		Revision as of 03:49, 16 December 2008
Line 13:		Line 13:
	MemTotal: 3368120 kB		MemTotal: 3368120 kB

-	This example RHEL 5 IA-32 system should definitely be using a PAE kernel.	+	This example RHEL 5 IA-32 system should definitely be using a PAE kernel, or using an x86_64 kernel and distribution.

	=== Processors ===		=== Processors ===

Hutch at 03:48, 16 December 2008

Hutch — Tue, 16 Dec 2008 03:48:50 GMT

←Older revision		Revision as of 03:48, 16 December 2008
Line 1:		Line 1:
	=== Physical memory ===		=== Physical memory ===

-	Situation: On an IA-32 (i386) Linux system without a PAE kernel, how can you be sure that the correct amount of physical memory is being returned by the kernel? Without a PAE kernel, the system will report a maximum of 4GB physical memory.	+	Situation: On an IA-32 (i386) Linux system without a PAE kernel, how can you be sure that the correct amount of physical memory is being returned by the kernel? Without a PAE kernel, the system will report a maximum of 4GB physical memory. Note that this does not apply to x86_64 kernels, as they can address more than 4GB physical memory.

	The easiest way I know of to determine the amount of physical memory in a Linux system is using '''dmidecode'''. The following works on RHEL 3, 4, and 5:		The easiest way I know of to determine the amount of physical memory in a Linux system is using '''dmidecode'''. The following works on RHEL 3, 4, and 5:

Hutch: New page: === Physical memory === Situation: On an IA-32 (i386) Linux system without a PAE kernel, how can you be sure that the correct amount of physical memory is being returned by the kernel? Wi...

Hutch — Tue, 16 Dec 2008 03:48:07 GMT

New page: === Physical memory === Situation: On an IA-32 (i386) Linux system without a PAE kernel, how can you be sure that the correct amount of physical memory is being returned by the kernel? Wi...

New page

=== Physical memory ===

Situation: On an IA-32 (i386) Linux system without a PAE kernel, how can you be sure that the correct amount of physical memory is being returned by the kernel? Without a PAE kernel, the system will report a maximum of 4GB physical memory.

The easiest way I know of to determine the amount of physical memory in a Linux system is using '''dmidecode'''. The following works on RHEL 3, 4, and 5:

# '''dmidecode | perl -ne '$memory += $1 if /^\t+Size: (\d+)/ ; END { print "$memory\n" }''''
8192

How much memory is being reported by the kernel?

# '''head -1 /proc/meminfo'''
MemTotal: 3368120 kB

This example RHEL 5 IA-32 system should definitely be using a PAE kernel.

=== Processors ===

Similarly, '''dmidecode''' may also be used to tell you the number of physical processors in a system. If you are running a uniprocessor kernel, the kernel will report one CPU regardless of how many you have.

It is very unlikely that you would be running a non-SMP kernel with multiple physical processors, but here's a way to return the actual number of physical processors in on a uniprocessor kernel. The following works on RHEL 2.1, 3, 4, and 5 (note that all kernels are SMP-enabled on RHEL 5):

# '''dmidecode | perl -ne '$num_procs += 1 if /^\t+Type: Central Processor/ ; END { print "$num_procs\n"}''''
2

=== Links ===

* [http://www.cyberciti.biz/tips/querying-dumping-bios-from-linux-command-prompt.html
Get Information About Your BIOS / Server Hardware From a Shell Without Opening Chassis ( BIOS Decoder )]