[PATCH v5 1/5] PID namespace translation support

[Dmitry V. Levin]

On Mon, Aug 03, 2020 at 09:19:12PM +0200, Ákos Uzonyi wrote:
[...]
> +void
> +pidns_init(void)
> +{
> +	if (proc_data_cache)
> +		return;
> +
> +	pid_max = INT_MAX;
> +	if (read_int_from_file("/proc/sys/kernel/pid_max", &pid_max) < 0)
> +		debug_func_perror_msg("reading /proc/sys/kernel/pid_max");
> +	pid_max_size = ilog2_32(pid_max - 1) + 1;
> +	pid_max_size_lg = ilog2_32(pid_max_size - 1) + 1;
> +
> +	for (int i = 0; i < PT_COUNT; i++)
> +		ns_pid_to_proc_pid[i] = trie_create(64, ptr_sz_lg, 10, 10, 0);

Has the numeric constant 64 been chosen because
sizeof(struct tcb.pid_ns) * 8 == 64?

> +
> +	proc_data_cache = trie_create(pid_max_size, ptr_sz_lg, 10, 10, 0);
> +}
> +
> +static void
> +put_proc_pid(uint64_t ns, int ns_pid, enum pid_type type, int proc_pid)
> +{
> +	struct trie *b = (struct trie *) (uintptr_t) trie_get(ns_pid_to_proc_pid[type], ns);
> +	if (!b) {
> +		b = trie_create(pid_max_size, pid_max_size_lg, 10, 10, 0);
> +		trie_set(ns_pid_to_proc_pid[type], ns, (uint64_t) (uintptr_t) b);
> +	}
> +	trie_set(b, ns_pid, proc_pid);
> +}

In all three cases trie_create is invoked with node_key_bits
and data_block_key_bits arguments equal to 10.

Could you shed some light on the choice of this numeric constant, please?


-- 
ldv