So I typed in lscpu into my terminal and saw this: CPU(s):              4 On-line CPU(s) list: 0-3 Thread(s) per core:  2 Core(s) per socket:  2 Socket(s):           1  The no. of CPU(s) is 4 here because of the formula: No. of CPUs = Sockets X Cores per socket X Threads per Core But the question is, what exactly is a CPU? Why are we including threads in the above formula?
123767
You can see the output from lscpu command -  jack@042:~$ lscpu Architecture:          x86_64 CPU op-mode(s):        32-bit, 64-bit Byte Order:            Little Endian CPU(s):                56 On-line CPU(s) list:   0-55 Thread(s) per core:    2 Core(s) per socket:    14 Socket(s):             2 NUMA node(s):          2 Vendor ID:             GenuineIntel CPU family:            6 Model:                 79 Model name:            Intel(R) Xeon(R) CPU E5-2690 v4 @ 2.60GHz Stepping:              1 CPU MHz:               2600.000 CPU max MHz:           2600.0000 CPU min MHz:           1200.0000 BogoMIPS:              5201.37 Virtualization:        VT-x Hypervisor vendor:     vertical Virtualization type:   full L1d cache:             32K L1i cache:             32K L2 cache:              256K L3 cache:              35840K NUMA node0 CPU(s):     0-13,28-41 NUMA node1 CPU(s):     14-27,42-55   I can see that there are 2 sockets (which is like a processor ??) and inside each of the socket we have 14 cores. So, in total 2x14=28 physical cores. Normally, a CPU can contain multiple cores, so number of CPUs can never be smaller than number of Cores. But, as shown in the output CPUs(s): 56 and this is what is confusing me.  I can see that Thread(s) per core:    2, so these 28 cores can behave like 2x28=56 logical cores.  Question 1: What does this CPUs(s): 56 denote? Does CPU(s) denote number of Virtual/Logical core, as it cannot be a Physical core core atleast?  Question 2: What does this NUMA node mean? Does it represent the socket?
13950
I'm just wondering where these values are being set and what they default to? Mine is currently 18446744073692774399. I didn't set it anywhere that I can see.  $ cat /proc/sys/kernel/shmmax  18446744073692774399  $ sysctl kernel.shmmax kernel.shmmax = 18446744073692774399
458
Could someone explain to me what a socket is? I see it in many acronyms in context of SSL, etc.  Also, why is it called a socket? Is it purely because it was what a name they invented? Or was it the first name they came up with?
26621
Looking at the  CPU, under Memory types it says "DDR3-1333/1600". My question is, in what way does the CPU limit the RAM speed? What would happen if I put in a DDR3-2133 RAM chip together with the CPU, if the motherboard supports the faster RAM speed? Would it be better to get a RAM chip that is DDR3-1600 so it matches the CPU's listed frequency?
115097
Cause Ubuntu uses Upstart instead of init, there is some different from Red Hat. But How can I get the list of each runlevel number standing for, such as init 0 means shutdown. man init can't show the list. So which command or man page cant print the list. Thx!
90439
On Linux 3.11.0-13-generic running on top of a dual socket Xeon X5650 hexa core board, htop shows different kworker threads. Sorted by names (I tweaked the result I am showing here a little bit to have the threads on core 2 before the ones on core 10), here is the result:  kworker/0:0H kworker/0:1 kworker/0:2 kworker/1:0 kworker/1:0H kworker/1:1 kworker/2:0 kworker/2:0H kworker/2:1 ..... kworker/11:0 kworker/11:0H kworker/11:1 kworker/u48:0 kworker/u49:4 kworker/u49:5 kworker/u50:1 kworker/u50:2 .......   The threads whose names start with a number are pinned to the core with the same number. So the first number is the core running the thread and I am wondering what the symbol after : (0 or 0H or 1) is for these threads?  I am also wondering what is the meaning of the uXX:Y symbols?  I have only a vague knowledge of what kworker threads do: they handle asynchronous events caused by system calls performing I/O. Are they documented somewhere?
15536
I want to compare (not precisely, no accurate benchmarking, just the big picture) two CPUs, the one of my main gaming PC (built in Feb 2011) and the one of my newest PC (built last week).  One has an Intel Core i7 870 and the other has an Intel Core i7 3630QM.  One would think that the new one would destroy the other or at least show a noticable difference, and I am only taking about their specifications, not even in practice! and it is not that obvious...  I mean when looking at the specs, the frequencies look close, the number of cores is the same, I mean what in the specs make one of those CPUs better that the other...  Comparing CPUs used to be way easier back in my days ;)
7166
How to limit process to one cpu core ?  Something similar to ulimit or cpulimit would be nice. (Just to ensure: I do NOT want to limit percentage usage or time of execution. I want to force app (with all it's children, processes (threads)) to use one cpu core (or 'n' cpu cores)).
113792
I have just ran lshw to get some information about  a machine I know nothing about, and I just wanted to confirm something.  Does this basically mean it is a dual core 64 bit processor that is installed?  *-logicalcpu:0     description: Logical CPU           physical id: 0.1               width: 64 bits               capabilities: logical        *-logicalcpu:1                 description: Logical CPU                physical id: 0.2                   width: 64 bits                capabilities: logical   Looking further down I see this    *-cpu:1       physical id: 1       bus info: cpu@1       version: 6.7.6       serial: 0001-0676-0000-0000-0000-0000       size: 3150MHz       capabilities: vmx ht       configuration: id=0     *-logicalcpu:0          description: Logical CPU          physical id: 0.1          capabilities: logical     *-logicalcpu:1          description: Logical CPU          physical id: 0.2          capabilities: logical   Which makes me almost certain it is dual core but not convinced on the 64 bit.  Any help for this n00b would be greatly appreciated!
97854
I have a dual core core i5 with hyperthreading. Since hyperthreading allows for unused cpu time to be used by other processes, why would this make it seem like 4 logical processors (2 per actual core). How is this different than out of order execution?  Lets say core0/core1 are one core and core2/core3 are another. If core0 and core2 are at 100% is my cpu at 100% load or only 50%? If all of them are at 100%, what does that entail? Also, how come processes tend to execute on core0 and core2 rather than core1 and core3?
21046
I run distributed computing projects, which typically want to use 100% of the CPU.  How do I limit the CPU usage in terms of temperature instead of percent usage?  Also, what is the maximum safe temperature to keep an Intel i5 running 24/7?  (With no CPU limit FahCore_a4 causes this machine to run at 82 degrees Celsius.)
60698
After reading alot of links, it bothers me that there is so much overlap between simple definitions such as CPU, processor, core, etc.       Let's clarify first what is a CPU and what is a core, a central processing unit CPU, can have multiple core units, those cores are a processor by itself, capable of execute a program but it is self contained on the same chip.        A CPU, or Central Processing Unit, is what is typically referred to as a processor.   So which one is it?  A CPU (central processing unit) contains (1-many) cores. Each core can execute (1-many) threads depending on hyper-threading technology - it does the actual computation sort to speak.  So what is a processor? Does it refer to the CPU, the entire chip as  a whole? Does it refer to one core on a CPU? And what exactly does multiprocessor/multicore mean? Are they synonymous?
64312
I am thinking of getting a dual Intel Xeon machine, each CPU is a quad core.  Will Ubuntu utilize both processors, especially with both being quad core, optimally?  Wanting to do Video editing and processing, but the Xeon machine's clock speed is actually slower than my current computer, so if both procs are not being used, I will actually end up with a slower machine than I already have.  I am not too familiar with dual processor machines. Thanks in advance for any answers.
9078
What is the technical difference between a process and a thread?  I get the feeling a word like 'process' is overused and there are also hardware and software threads. How about light-weight processes in languages like ? Is there a definitive reason to use one term over the other?
12685
What happens when I write cat /proc/cpuinfo. Is that a named pipe (or something else) to the OS which reads the CPU info on the fly and generate that text each time I call it?
80044
As much as I have read about iowait, it is still mystery to me.  I know it's the time spent by the CPU waiting for a IO operations to complete, but what kind of IO operations precisely? What I am also not sure, is why it so important? Can't the CPU just do something else while the IO operation completes, and then get back to processing data?  Also what are the right tools to diagnose what process(es) did exactly wait for IO.  And what are the ways to minimize IO wait time?
23733
I know about the "cooperative" threading of ruby using . How can I create real "OS-level" threads in my application in order to make use of multiple cpu cores for processing?