Receiving information about CPU time and memory usage

The libkos library provides an API that lets you receive information about CPU time and memory usage. This API is defined in the header file sysroot-*-kos/include/coresrv/stat/stat_api.h from the KasperskyOS SDK.

To get information about CPU time and memory usage and other statistical data, you need to build a solution with a KasperskyOS kernel version that supports performance counters. For more details, refer to "Image library".

Receiving information about CPU time

CPU uptime is counted from the startup of the KasperskyOS kernel.

To receive information about CPU time, you need to use the KnGroupStatGetParam() and KnTaskStatGetParam() functions. The values provided in the table below need to be passed in the param parameter of these functions.

Information about CPU time

Function	Value of the param parameter	Obtained value
KnGroupStatGetParam()	GROUP_PARAM_CPU_KERNEL	CPU uptime in kernel mode
KnGroupStatGetParam()	GROUP_PARAM_CPU_USER	CPU uptime in user mode
KnGroupStatGetParam()	GROUP_PARAM_CPU_IDLE	CPU uptime in idle mode
KnTaskStatGetParam()	TASK_PARAM_TIME_TOTAL	CPU uptime spent on process execution
KnTaskStatGetParam()	TASK_PARAM_TIME_USER	CPU uptime spent on process execution in user mode

The CPU uptime obtained by calling the KnGroupStatGetParam() or KnTaskStatGetParam() function is presented in nanoseconds.

Receiving information about memory usage

To receive information about memory usage, you need to use the KnGroupStatGetParam() and KnTaskStatGetParam() functions. The values provided in the table below need to be passed in the param parameter of these functions.

Information about memory usage

Function	Value of the param parameter	Obtained value
KnGroupStatGetParam()	GROUP_PARAM_MEM_TOTAL	Total size of all installed RAM
KnGroupStatGetParam()	GROUP_PARAM_MEM_FREE	Size of free RAM
KnTaskStatGetParam()	TASK_PARAM_MEM_PHY	Size of RAM used by the process

The memory size obtained by calling the KnGroupStatGetParam() or KnTaskStatGetParam() function is presented as the number of memory pages. The size of a memory page is 4 KB for all hardware platforms supported by KasperskyOS.

The amount of RAM used by a process refers only to the memory allocated directly for this process. For example, if the memory of a process is mapped to an MDL buffer created by another process, the size of this buffer is not included in this value.

Enumerating processes

To get information about CPU time and memory usage by each process, do the following:

1. Get the list of processes by calling the KnGroupStatGetTaskList() function.
2. Get the number of items on the list of processes by calling the KnTaskStatGetTasksCount() function.
3. Iterate through the list of processes, repeating the following steps:
   1. Get an item from the list of processes by calling the KnTaskStatEnumTaskList() function.
   2. Get the process name by calling the KnTaskStatGetName() function.

      This is necessary to identify the process for which the information about CPU time and memory usage will be received.

   3. Get information about CPU time and memory usage by calling the KnTaskStatGetParam() function.
   4. Verify that the process was not terminated. If the process was terminated, do not use the obtained information about CPU time and memory usage by this process.

      To verify that the process was not terminated, you need to call the KnTaskStatGetParam() function, using the param parameter to pass the TASK_PARAM_STATE value. A value other than TaskStateTerminated should be received.

   5. Finish working with the item on the list of processes by calling the KnTaskStatCloseTask() function.
4. Finish working with the list of processes by calling the KnTaskStatCloseTaskList() function.

Calculating CPU load

CPU load can be indicated as a percentage of total CPU load or as a percentage of CPU load by each process. These indicators are calculated for a specific time interval, at the start and end of which the information about CPU time utilization was received. (For example, CPU load can be monitored with periodic receipt of information about CPU time utilization.) The values obtained at the start of the interval need to be subtracted from the values obtained at the end of the interval. In other words, the following increments need to be obtained for the interval:

• TK – CPU uptime in kernel mode.
• TU – CPU uptime in user mode.
• TIDLE – CPU uptime in idle mode.
• Ti [i=1,2,...,n] – CPU time spent on execution of the ith process.

The percentage of total CPU load is calculated as follows:

(TK+TU)/(TK+TU+TIDLE).

The percentage of CPU load by the ith process is calculated as follows:

Ti/(TK+TU+TIDLE).

Receiving additional information about processes

In addition to information about CPU time and memory usage, the KnGroupStatGetParam() and KnTaskStatGetParam() functions also let you obtain the following information:

• Number of processes
• Number of threads
• Number of threads in one process
• Parent process ID (PPID)
• Process priority
• Number of handles owned by a process
• Size of virtual memory of a process

The KnTaskStatGetId() function gets the process ID (PID).

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