ckernel_alloc_v6.5.c File Reference

#include "ckernel_alloc.h"
#include <errno.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <unistd.h>

Go to the source code of this file.

Macros
#define	_GNU_SOURCE
#define	HUGE_PAGE_SIZE   (2UL * 1024UL * 1024UL)

Functions
static size_t	align_up_bytes (size_t n, size_t align)
void *	ck_huge_alloc (size_t bytes)
void	ck_huge_free (void *ptr, size_t bytes)
static ck_huge_alloc_entry_t *	detach_allocation (void *ptr)
static int	record_allocation (void *ptr, size_t len, int was_mmap)

Variables
static ck_huge_alloc_entry_t *	g_alloc_list = NULL
static pthread_mutex_t	g_alloc_mutex = PTHREAD_MUTEX_INITIALIZER

Macro Definition Documentation

_GNU_SOURCE

#define _GNU_SOURCE

Definition at line 1 of file ckernel_alloc_v6.5.c.

HUGE_PAGE_SIZE

#define HUGE_PAGE_SIZE   (2UL * 1024UL * 1024UL)

Definition at line 15 of file ckernel_alloc_v6.5.c.

Function Documentation

align_up_bytes()

static size_t align_up_bytes ( size_t  n, size_t  align  )

static

Definition at line 28 of file ckernel_alloc_v6.5.c.

{
    if (align == 0) return n;
    return (n + align - 1) & ~(align - 1);
}

Referenced by ck_huge_alloc().

ck_huge_alloc()

void* ck_huge_alloc

(

size_t

bytes

)

Allocate a large, contiguous memory region for model weights/activations.

Implementation strategy:

• Try to allocate 2MB-aligned memory backed by huge pages where possible.
• Fall back to aligned_alloc + madvise(MADV_HUGEPAGE) when explicit huge pages are not available.

Returns NULL on failure.

Definition at line 67 of file ckernel_alloc_v6.5.c.

{
    size_t len = align_up_bytes(bytes, HUGE_PAGE_SIZE);
 
    /* First, try explicit huge pages via mmap + MAP_HUGETLB. */
    void *p = mmap(NULL, len,
                   PROT_READ | PROT_WRITE,
                   MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB,
                   -1, 0);
    if (p != MAP_FAILED) {
        if (!record_allocation(p, len, 1)) {
            munmap(p, len);
            return NULL;
        }
        return p;
    }
 
    /* Fallback: aligned_alloc with transparent hugepage hint. */
    void *q = aligned_alloc(HUGE_PAGE_SIZE, len);
    if (!q) {
        fprintf(stderr, "ck_huge_alloc: aligned_alloc failed for %zu bytes: %s\n",
                len, strerror(errno));
        return NULL;
    }
 
    /* Best-effort hint; ignore errors. */
    (void)madvise(q, len, MADV_HUGEPAGE);
    if (!record_allocation(q, len, 0)) {
        free(q);
        return NULL;
    }
    return q;
}

References align_up_bytes(), HUGE_PAGE_SIZE, and record_allocation().

ck_huge_free()

void ck_huge_free	(	void *	ptr,
		size_t	bytes
	)

Free memory allocated by ck_huge_alloc.

The bytes parameter should be the same size passed to ck_huge_alloc.

Definition at line 101 of file ckernel_alloc_v6.5.c.

{
    if (!ptr || bytes == 0) {
        return;
    }
 
    ck_huge_alloc_entry_t *entry = detach_allocation(ptr);
    if (!entry) {
        /* Fall back to malloc/free if the allocation wasn't tracked. */
        free(ptr);
        return;
    }
 
    if (entry->was_mmap) {
        munmap(ptr, entry->len);
    } else {
        free(ptr);
    }
 
    free(entry);
}

References detach_allocation().

detach_allocation()

static ck_huge_alloc_entry_t* detach_allocation ( void *  ptr )

static

Definition at line 50 of file ckernel_alloc_v6.5.c.

{
    pthread_mutex_lock(&g_alloc_mutex);
    ck_huge_alloc_entry_t **node = &g_alloc_list;
    while (*node) {
        if ((*node)->ptr == ptr) {
            ck_huge_alloc_entry_t *entry = *node;
            *node = entry->next;
            pthread_mutex_unlock(&g_alloc_mutex);
            return entry;
        }
        node = &(*node)->next;
    }
    pthread_mutex_unlock(&g_alloc_mutex);
    return NULL;
}

References g_alloc_list, and g_alloc_mutex.

Referenced by ck_huge_free().

record_allocation()

static int record_allocation ( void *  ptr, size_t  len, int  was_mmap  )

static

Definition at line 34 of file ckernel_alloc_v6.5.c.

{
    ck_huge_alloc_entry_t *entry = malloc(sizeof(*entry));
    if (!entry) {
        return 0;
    }
    entry->ptr = ptr;
    entry->len = len;
    entry->was_mmap = was_mmap;
    pthread_mutex_lock(&g_alloc_mutex);
    entry->next = g_alloc_list;
    g_alloc_list = entry;
    pthread_mutex_unlock(&g_alloc_mutex);
    return 1;
}

References g_alloc_list, and g_alloc_mutex.

Referenced by ck_huge_alloc().

Variable Documentation

g_alloc_list

ck_huge_alloc_entry_t* g_alloc_list = NULL

static

Definition at line 26 of file ckernel_alloc_v6.5.c.

Referenced by detach_allocation(), and record_allocation().

g_alloc_mutex

pthread_mutex_t g_alloc_mutex = PTHREAD_MUTEX_INITIALIZER

static

Definition at line 25 of file ckernel_alloc_v6.5.c.

Referenced by detach_allocation(), and record_allocation().