pg_numa.c

Go to the documentation of this file.

/*-------------------------------------------------------------------------
 *
 * pg_numa.c
 *      Basic NUMA portability routines
 *
 *
 * Copyright (c) 2025, PostgreSQL Global Development Group
 *
 *
 * IDENTIFICATION
 *    src/port/pg_numa.c
 *
 *-------------------------------------------------------------------------
 */
 
#include "c.h"
#include <unistd.h>
 
#include "port/pg_numa.h"
 
/*
 * At this point we provide support only for Linux thanks to libnuma, but in
 * future support for other platforms e.g. Win32 or FreeBSD might be possible
 * too. For Win32 NUMA APIs see
 * https://learn.microsoft.com/en-us/windows/win32/procthread/numa-support
 */
#ifdef USE_LIBNUMA
 
#include <numa.h>
#include <numaif.h>
 
/* libnuma requires initialization as per numa(3) on Linux */
int
pg_numa_init(void)
{
    int         r = numa_available();
 
    return r;
}
 
/*
 * We use move_pages(2) syscall here - instead of get_mempolicy(2) - as the
 * first one allows us to batch and query about many memory pages in one single
 * giant system call that is way faster.
 */
int
pg_numa_query_pages(int pid, unsigned long count, void **pages, int *status)
{
    return numa_move_pages(pid, count, pages, NULL, status, 0);
}
 
int
pg_numa_get_max_node(void)
{
    return numa_max_node();
}
 
#else
 
/* Empty wrappers */
int
pg_numa_init(void)
{
    /* We state that NUMA is not available */
    return -1;
}
 
int
pg_numa_query_pages(int pid, unsigned long count, void **pages, int *status)
{
    return 0;
}
 
int
pg_numa_get_max_node(void)
{
    return 0;
}
 
#endif