Re: [RFC PATCH v2 3/5] futex: Throughput-optimized (TO) futexes

From: Peter Zijlstra
Date: Thu Sep 22 2016 - 09:23:59 EST


On Tue, Sep 20, 2016 at 09:42:41AM -0400, Waiman Long wrote:
> +/*
> + * Spinning threshold before enabling lock handoff.
> + * Each sleep will decrement the threshold by 1/32 of the start value.
> + */
> +#define TO_SPIN_THRESHOLD (1 << 13)
> +#define TO_SLEEP_DECREMENT (TO_SPIN_THRESHOLD/32)

Argh, we should really get rid of those stupid numbers. Wasn't there a
patch set working on implementing paravirt functions that would make all
this fixable in a sane way?