How to programmatically get the CPU cache page size in C++?

Question

I'd like my program to read the cache line size of the CPU it's running on in C++.

I know that this can't be done portably, so I will need a solution for Linux and another for Windows (Solutions for other systems could be usefull to others, so post them if you know them).

For Linux I could read the content of /proc/cpuinfo and parse the line begining with cache_alignment. Maybe there is a better way involving a call to an API.

For Windows I simply have no idea.

Thanks for your help.

Answer 1

Looks like at least SCO unix (http://uw714doc.sco.com/en/man/html.3C/sysconf.3C.html) has _SC_CACHE_LINE for sysconf. Perhaps other platforms have something similar?

Answer 2

On Win32, GetLogicalProcessorInformation will give you back a SYSTEM_LOGICAL_PROCESSOR_INFORMATION which contains a CACHE_DESCRIPTOR, which has the information you need.

Answer 3

I think you need NtQuerySystemInformation from ntdll.dll.

Answer 4

For x86, the CPUID instruction. A quick google search reveals some libraries for win32 and c++. I have used CPUID via inline assembler as well.

Some more info:

• http://www.intel.com/Assets/PDF/appnote/241618.pdf
• http://softpixel.com/~cwright/programming/simd/cpuid.php

Answer 5

On Linux try the proccpuinfo library, an architecture independent C API for reading /proc/cpuinfo