linux-kernel - Re: [RFC 7/7] x86/current: Aggressive caching of current

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Message-ID: <20190722210704.GL6698@worktop.programming.kicks-ass.net>
Date:   Mon, 22 Jul 2019 23:07:04 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Nadav Amit <namit@...are.com>
Cc:     Andy Lutomirski <luto@...nel.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>
Subject: Re: [RFC 7/7] x86/current: Aggressive caching of current

On Thu, Jul 18, 2019 at 10:41:10AM -0700, Nadav Amit wrote:
> The current_task is supposed to be constant in each thread and therefore
> does not need to be reread. There is already an attempt to cache it
> using inline assembly, using this_cpu_read_stable(), which hides the
> dependency on the read memory address.

Is that what it does?!, I never quite could understand
percpu_stable_op().