What is the difference between hyper-threading and multi-threading?

What is the difference between hyper-threading and multi-threading?

超线程从硬件层面理解，即一个CPU的部件（可以理解为核）同时执行多条指令，表现就是同时执行多个线程。
多线程是软件层面的概念，比如CPU只有一个核，通过线程调度可以在一个时间段内运行多个程序或任务，但实际任何时刻只执行一个线程。

In a Linux system, how to learn more about the CPU information? Of course, it is checked through cat /proc/cpuinfo, but for example, how many physical CPUs/cores/threads are there? How to determine these problems?

After checking, my development machine has 1 physical CPU, 4 cores and 8 threads, Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz www.2cto.com

Record it and judge process and knowledge.

Judgment basis:

1. CPUs with the same core id are hyper-threaded by the same core.

2. CPUs with the same physical ID are threads or cores encapsulated by the same CPU.

English version:

1.Physical id and core id are not necessarily consecutive but they are unique. Any cpu with the same core id are hyperthreads in the same core.

2.Any cpu with the same physical id are threads or cores in the same physical socket.

echo "logical CPU number:"

#number of logical CPUs

cat /proc/cpuinfo | grep "processor" | wc -l

echo "physical CPU number:"

#Physical CPU number:

cat /proc/cpuinfo | grep "physical id" | sort | uniq | wc -l

echo "core number in a physical CPU:"

#The number of Cores in each physical CPU:

cat /proc/cpuinfo | grep "cpu cores" | uniq | awk -F: '{print $2}'

# Check the number of core ids on each physical CPU, which is the number of cores on each physical CPU.

cat /proc/cpuinfo | grep "core id"

# Is it Hyper-threading?

#If there are two logical CPUs with the same "core id", then hyperthreading is turned on.

#The number of logical CPUs (may be core, threads or both) in each physical CPU:

cat /proc/cpuinfo | grep "siblings"

/proc/cpuinfo The file contains sections of data for each processor on the system. There are 6 entries in the /proc/cpuinfo description that apply to multi-core and hyper-threading (HT) technology checks: processor, vendor id, physical id, siblings, core id and cpu cores. The

processor entry contains the unique identifier of this logical processor.

The physical id entry contains a unique identifier for each physical package.

The core id entry holds a unique identifier for each core. The

siblings entry lists the number of logical processors located in the same physical package.

The cpu cores entry contains the number of cores located in the same physical package.

If the processor is an Intel processor, the string in the vendor id entry is GenuineIntel.

1. All logical processors with the same physical ID share the same physical socket. Each physical id represents a unique physical package.

2.Siblings represents the number of logical processors located on this physical package. They may or may not support Hyper-Threading (HT) technology.

3. Each core id represents a unique processor core. All logical processors with the same core id are on the same processor core.

4. If there is more than one logical processor with the same core id and physical id, it means that the system supports hyper-threading (HT) technology.

5. If there are two or more logical processors with the same physical ID but different core IDs, it means this is a multi-core processor. The cpu cores entry can also indicate whether multiple cores are supported.

To determine whether the CPU is 64-bit, check the flags section in cpuinfo to see if there is an lm mark.

Are the processors 64-bit?

A 64-bit processor will have lm ("long mode") in the flags section of cpuinfo. A 32-bit processor will not.

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