τₙ₊₁ = α × tₙ + (1 - α) × τₙ

where:
  tₙ = actual time of last burst
  τₙ = predicted time of last burst
  α  = weight (typically 0.5)

// Lower number = higher priority (typical convention)
struct process {
    int pid;
    int priority;
    int burst_time;
};

// Priority assignment factors:
// - Static: user-defined, process type
// - Dynamic: aging, I/O behavior, CPU usage

void age_priorities(Process *ready_queue, int count) {
    for (int i = 0; i < count; i++) {
        ready_queue[i].priority += ready_queue[i].wait_time / AGING_FACTOR;
    }
}

// Each task has a virtual runtime (vruntime)
// CFS always runs the task with lowest vruntime

struct sched_entity {
    struct rb_node run_node;  // Position in red-black tree
    u64 vruntime;             // Virtual runtime
    u64 sum_exec_runtime;     // Actual runtime
    // ...
};

// vruntime increases as task runs:
// vruntime += delta_exec * (NICE_0_WEIGHT / task_weight)

// Higher priority (lower nice) → lower weight → vruntime increases slower
// → task gets more CPU time

Nice value:  -20 ─────────── 0 ─────────── +19
Priority:    HIGH            NORMAL        LOW
Weight:      88761          1024           15

// A nice -20 task gets ~88761/1024 ≈ 87x more CPU than nice 0
// A nice +19 task gets ~15/1024 ≈ 1/68x as much CPU as nice 0

#include <sched.h>

struct sched_param param;
param.sched_priority = 99;  // 1-99, higher = more urgent

// FIFO: runs until it voluntarily yields or blocks
sched_setscheduler(pid, SCHED_FIFO, &param);

// Round-robin: like FIFO but with time slicing among same priority
sched_setscheduler(pid, SCHED_RR, &param);

#define _GNU_SOURCE
#include <sched.h>

// Set CPU affinity
cpu_set_t cpuset;
CPU_ZERO(&cpuset);
CPU_SET(0, &cpuset);  // Allow only CPU 0
CPU_SET(2, &cpuset);  // Also allow CPU 2

sched_setaffinity(pid, sizeof(cpuset), &cpuset);

// Get current affinity
sched_getaffinity(pid, sizeof(cpuset), &cpuset);
for (int i = 0; i < CPU_SETSIZE; i++) {
    if (CPU_ISSET(i, &cpuset)) {
        printf("Process can run on CPU %d\n", i);
    }
}

#include <numaif.h>

// Allocate memory on specific node
void *ptr = numa_alloc_onnode(size, node);

// Set memory policy
unsigned long nodemask = 1 << 0;  // Node 0
set_mempolicy(MPOL_BIND, &nodemask, sizeof(nodemask) * 8);

// Move pages to specific node
move_pages(pid, count, pages, nodes, status, MPOL_MF_MOVE);