[ovs-discuss] Kernel vs User mode switch

[Daniel Lohin]

No idea what you are talking about… in what?

Generally speaking…  a user application runs as fast as kernel, as long as it doesn’t need to make system level calls (i.e. write files, network packets, etc).  The reason is the kernel needs to do a lot of things like, does the person have permissions…  This is called context switching.

Running at the kernel level is always fast…  there is never any context switching..

now for the drawback… errors in programming in the kernel are disasterous… major system crashes (the whole computer), really bad security issues, etc…  User mode is a lot safer, at least to the system itself (an error can still result in the crashing of the app, or security problems with the app itself, but not the entire system).

We try to keep as much out of the kernel as possible, but there are some areas where it is needed for performance reasons.  

> On Mar 26, 2017, at 8:33 PM, Michael Williams <mw7301 at hotmail.com> wrote:
> 
> What are the advantages of running the kernel verses  the user mode switch?
> 

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