Date: Thu, 16 Oct 2025 17:19:52 +0200
From: Christoph Berg <myon@debian.org>
To: Tomas Vondra <tomas@vondra.me>
Cc: Jakub Wartak <jakub.wartak@enterprisedb.com>,
	pgsql-hackers@lists.postgresql.org
Subject: Re: failed NUMA pages inquiry status: Operation not permitted
Message-ID: <aPENGAkcrLyB_NLC@msg.df7cb.de>
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> So maybe all that's needed is a get_mempolicy() call in
> pg_numa_available() ?

numactl 2.0.19 --show does this:

        if (numa_available() < 0) {
                show_physcpubind();
                printf("No NUMA support available on this system.\n");
                exit(1);
        }

int numa_available(void)
{
        if (get_mempolicy(NULL, NULL, 0, 0, 0) < 0 && (errno == ENOSYS || errno == EPERM))
                return -1;
        return 0;
}

pg_numa_available is already calling numa_available.

But numactl 2.0.16 has this:

int numa_available(void)
{
	if (get_mempolicy(NULL, NULL, 0, 0, 0) < 0 && errno == ENOSYS)
		return -1;
	return 0;
}

... which is not catching the "permission denied" error I am seeing.

So maybe PG should implement numa_available itself like that. (Or
accept the output difference so the regression tests are passing.)

Christoph