[Devel] Re: [RFC PATCH v2] posix timers: allocate timer id per task

[Eric Dumazet]

On Wed, 2012-10-17 at 17:18 +0400, Stanislav Kinsbursky wrote:

> +static int hash(struct signal_struct *sig, unsigned int nr)
> +{
> +	int hash = hash_ptr(sig, POSIX_TIMERS_HASH_BITS);
> +	return hash ^ hash_32(nr, POSIX_TIMERS_HASH_BITS);
> +}
> +

This is quite expensive on 64 bit arches. I suggest instead :

return hash_32(hash32_ptr(sig) ^ nr, POSIX_TIMERS_HASH_BITS);