Most production systems have a method showing CPU usage. Windows, this method is Task Manager.

what is kernel mode user mode

CPU utilization is mainly represented by a simple percentage of CPU time spent in non-idle activities. But this is a little oversimplified. In every modern system, the processor actually has to pay for time in two very different modes:

  1. Kernel mode

    In kernel mode, the running promo code has full and unlimited access to the base material. He can provide any link to instruction CN and almost any memory address. Kernel mode is mostly reserved at the lowest level and is most dependent on the functions of the operating system. Kernel mode crashes are catastrophic; he or she will shut down the entire computer.

  2. Custom mode

    In user mode, the execution code does not have the ability to directly access reference hardware or PC memory. User-mode code must be delegated by the system using an API to access hardware or memory. With the protection provided by this type of isolation, user mode failures can always be corrected. Most of the code that runs on any computer is executed in PC operator mode.

It is possible to enable the display of the kernel time in the task manager, as in the screenshot above. The green line is the total processor time; red definitely indicates core time. The gap between two users is time.

These two modes are, of course, just designations; They are applied by the CPU hardware. When the builder of theUser mode tries to do something outside of its jurisdiction — for example, speak, access a privileged CPU instruction, or otherwise alter memory that it does not have access to — a fixable omission occurs. Instead of crashing your entire system, only a specific implementation crashes. This is a precious user mode.

what is kernel mode user mode

In fact, the x86-CPU offers hardware with four rings of protection: 0, 1, 2, and 3. Usually only rings (core) 0 and 3 (custom) are used.

Now, if we’re just using two electrical and artistic ribbons, it’s a little tricky to figure out where the device drivers should go – the code that usually allows us to use our video cards, keyboards, mice, printers, and so on, etc., etc. E. Do these drivers run in kernel mode for maximum performance or, if that fails, in user mode for maximum stability? On Windows, the answer is at least the one by which it is determined. Device drivers can run in a custom kernel or mode. At the same timeIn some cases, most drivers must bypass the user-side barrier, with the exception of video card drivers, which require kernel-mode performance. But that, too, has always changed; In Windows Vista, graphics drivers are divided into “Users” and “Partitions” kernels. Perhaps this is why complaining players play Vista about 10% slower.

The line between these regimes is still absurdly blurred. What code should I run in user mode? What code should I run in kernel mode? Or maybe we are unlikely to redefine land as a zone – the rise of virtualization has led to the creation of a new ring that follows everyone else, ring -1, which we know today as x86 device virtualization.

User Mode is certainly in the public domain of the Internet, but you have to pay for it. The transition between user mode and therefore kernel mode is expensive. Very expensive. This is why, for example, software that handles exceptions is slow. Exceptions are related to transitions from the modeto the core. Of course, we have so much power now that we rarely have to worry about the strength of the adjustment, but if you end up wanting strength, you will certainly start worrying about those things.

Probably the most public example of a custom line or core redesign is in web servers. Microsoft IIS 6 ported much of its core functionality into a kernel routine, especially after the desired open source web server used kernel mode to showcase a major industry win. It was kind of a war, completely unfounded if you ask me, since all core optimizations (in both camps) are ideally applicable to static HTML content. But this is the path of just wars, milestones or other attractions.

The strict separation of processor code between user mode and kernel mode is completely transparent to most of us, but most likely it will literally be the difference between a computer that constantly crashes and a computer that crashes catastrophically. It’s just for us, the authors of the code with increased emergencyost, I like to “progress”. On behalf of many programmers around the world, I would like to testify about the user gratitude mode. You are burning!