On Bang (as well as most other Linux systems) the lscpu command reports the processor's memory hierarchy. Note that for private caches (such as L1 and L2) you need to multiply the reported cache size by the number of cores, to obtain the total cache size at a given level. The output doesn't tell you which caches are duplicated, so you'll need to dig deeper to get this information .
In addition to the lscpu command, there is also a file called /proc/cpuinfo, which provides a variety of other information. For example, here is part of Bang's cpuinfo file:
cpu family : 6 model : 15 model name : Intel(R) Xeon(R) CPU E5345 @ 2.33GHz stepping : 7 cpu MHz : 2333.331
The contents of cpuinfo enables you to identify the specific processor, and the identifying information may be used to obtain other details from on-line resources. This information confirms that a Bang node contains quad-core 2.33GHz Intel Xeon E5345 processor. There is additional information in procinfo: family, model, and stepping. So in this case the family is 6, the model is 16, and the stepping is 7. This will allow you to explore smaller scale changes to the processor’s design that occurred over time.
We may learn more by accessing Intel's ARK Database. Once at the ARK web site, search on "E5345" in the search window at the top of the page. You'll obtain various information; for example, the processor has 4 cores, and a 8 MB unified (instructions + data) L2 cache shared among all cores. (The 2.33 GHz clock speed matches that listed in the cpuinfo file). The L1 cache size, not listed, is 32KB per core; separate instruction and data caches.
Unfortunately, Intel dropped the handy processor finder web site (CPU World maintains similar functionality if you know the S-Number). However, you may obtain more detailed information about the processor in another way. There is set of files providing detailed characteristics of all levels of cache (though there are many files):
/sys/devices/system/cpu/cpu*/cache/index*/*
This information further verifies that each pair of cores shares 4MB of L2 cache.
The definitive source of information about Intel processors Intel 64 and IA-32 Architectures Optimization Reference Manual, (July 2013), where you can find detailed information about your processor.
This document is accessible from another page that Intel maintains with pointers to a several documents on Intel 64 and IA-32 Architectures Software Developer Manuals
Though we will be using Intel processors in this course, some of you may have access to alternatives, such as AMD or Nvidia. More information about AMD processors can be found at the AMD Developer site. For information about Nvidia processsors, see the Nvidia developer site.
[Mon Jan 4 06:45:01 PST 2016 ]