A high-efficiency, real-time system telemetry tool developed in C. This utility bypasses traditional overhead by interfacing directly with the Linux Kernel via the /proc virtual filesystem, providing a live dashboard of hardware utilization and process lifecycle management.
Instead of relying on heavy external libraries, this tool performs raw parsing of kernel-exported data:
- /proc/stat: Used for global CPU work-unit analysis.
- /proc/meminfo: Used for physical memory page statistics.
- /proc/[PID]/stat: Used for individual process threading and state metadata.
The monitor calculates CPU load using a differential snapshot method. Since /proc/stat provides cumulative "jiffies" (clock ticks) since boot, the program:
- Captures a baseline of
workandidleticks. - Waits for a 1-second interval.
- Calculates the delta (
$\Delta$ ):$$\text{Usage %} = \left( \frac{\Delta \text{Total} - \Delta \text{Idle}}{\Delta \text{Total}} \right) \times 100$$
To maintain a near-zero memory footprint, the application utilizes fscanf with assignment suppression (%*). This allows the "reading head" to skip unnecessary kernel data fields directly in the buffer without allocating RAM for temporary variables.
The application implements a strict 1-to-1 mapping of the Linux Process Specification to reach field index 20 (Thread Count):
| Position | Specifier | Description | Action |
|---|---|---|---|
| 1 | %*d |
PID | Ignored (extracted from directory) |
| 2 | (%[^)]) |
Command | Stored (Regex-style capture) |
| 3 | %c |
State | Stored (R=Run, S=Sleep, D=Wait) |
| 4-19 | %*d/%*u |
Kernel Metadata | Ignored (sequential skip) |
| 20 | %d |
Thread Count | Stored |
The UI utilizes ANSI Escape Sequences to create a persistent dashboard. By using \033[H (Cursor Home) and \033[J (Clear from cursor), the program overwrites the existing terminal buffer. This technique:
- Eliminates screen flickering.
- Reduces I/O system calls by updating only once per cycle.
- Preserves terminal history above the program execution point.
- OS: Linux (Kernel 2.6.x+)
- Compiler: GCC 4.8+ or Clang
- Standards: C99 or later
Utilize the -O3 flag for maximum compiler optimization regarding loop unrolling and branch prediction:
gcc -O3 main.c -o sys_monitor