Linux Kernel Network Subsystem Patching

[Bob Jonkman]

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Thanx, Len.

> Multithreading is multiple threads in a process.  Every process
> has at least one thread

Even a single, 1-core processor can run multi-threaded code, can't it?
I imagine by the OS timeslicing.  The Amiga was the computer I saw
where someone pointed out the pitfalls of multi-threading, and I'm
sure that didn't have multi-core. But I expect that code that runs
multi-threaded on a 1-core processor would run better on a multi-core
processor.

How much code tweaking is necessary for a multi-threaded program to
take advantage of multiple cores? Or does the compiler take care of that?

- --Bob.


On 14-01-21 05:42 PM, Lennart Sorensen wrote:
> On Tue, Jan 21, 2014 at 04:26:24PM -0500, Bob Jonkman wrote:
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>> 
>> Is there a difference between hyperthreading and multithreading?
>> 
>> (Not a snark -- I really don't know, and would like to...)
> 
> Hyperthreading is one way to give you multiple hardware threads. 
> Actual seperate cores is another way.  To software there is no 
> difference between a CPU core and a CPU thread.  Every core has at 
> least one hardware thread.  Hyperthreading gives each core 2 
> threads (in all current implementations).  power6 has 2 threads per
> core of SMT, and power7 has 4 threads per core.  power8 is likely
> to have 8 threads per core.
> 
> Multithreading is multiple threads in a process.  Every process
> has at least one thread (if it has more than the first one, then it
> is a multithreaded program).  The system runs one thread on one CPU
> at any given time, so a multithreaded program could be using
> multiple cores at once, or at least multiple hardware threads on a
> core.
> 
> The hardware threads share some resources, such as execution
> units, but do not share CPU registers.  Each CPU core on the other
> hand is independant (in general.  AMD's newer chips is starting the
> share the FPU between two cores in interesting ways, without
> sharing anything else).
> 
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