December 7, 201510 yr I noticed this when recently setting about a Windows VM in Unraid 6.1.6 The VM set up asks you to set the number of cores you want available. The VM title bar lists them as CPUs which I believe to be incorrect.
December 7, 201510 yr I noticed this when recently setting about a Windows VM in Unraid 6.1.6 The VM set up asks you to set the number of cores you want available. The VM title bar lists them as CPUs which I believe to be incorrect. Actually it's the other way around as gary will undoubtedly remind me ;-). To linux, CPUs are available threads on the processor. This means a normal CPU is 1:1 physical threads to logical CPUs. With hyperthreading, it would be a 1:2 ratio of physical theads to logical CPUs. We will fix the description in a future update.
December 8, 201510 yr I'll add my nickel's worth ==> the stewman is correct. CPU technically refers to the physical chip. Most systems folks build for UnRAID have a single CPU, although a few folks have built systems with dual-CPU motherboards (typically using dual 2011 motherboards with a pair of Xeon E5's). Cores refers to the number of processor cores that the CPU has => most modern CPUs have at least 2 cores, often 4, and at the upper end can have 6, 8, or even more (Xeons have up to 18 cores). Many Intel CPU's also support hyperthreading -- a technology where they build two complete sets of registers for each core and logic that makes task-switching nearly transparent, so they can switch between threads nearly instantaneously. These are NOT additional cores ... i.e. there's no extra "processing power" involved ... but it can help speed things up by allowing two threads to efficiently share the same processor core. What Jon undoubtedly is referring to is when he called an i7 an "8 core processor" in a presentation he gave -- which is clearly NOT the case. It's a 4-core hyperthreaded processor ... which will "look" like 8 CPU's in Windows' Task Manager Performance tab. But it's ONE hyperthreaded 4-core CPU If you built a system with two 18-core hyperthreaded Xeons you'd have a system with 2 CPUs supporting 36 cores and 72 threads [This would, of course, be a SLICK system !! ... but 18-core E5 Xeons are ~ $5,000 each (~ $7500 for the new E7's), so I don't think many folks are likely to build anything close to this for an UnRAID server :) ] To confuse things, both Windows' Task Manager and the Linux processor displays show each thread as a "CPU". I think it's more accurate to call them "processors" (as VMware does) ... but even that is a bit of a misnomer, since each thread doesn't really have it's own core. I think the best term to use for a thread is "logical processor" -- this matches the terminology used in Windows Server editions. One minor correction, r.e. With hyperthreading, it would be a 1:2 ratio of physical theads to logical CPUs. NO. it's a 1:2 ratio of physical cores to logical processors (or CPUs if you prefer). NOT threads (which is a software distinction that refers to how the OS is managing the task flow).
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