linux-kernel - Re: [PATCH 5/5] arm64: Remove TIF

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Date:   Tue, 18 Feb 2020 08:57:09 +0000
From:   Will Deacon <will@...nel.org>
To:     Frederic Weisbecker <frederic@...nel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Paul Burton <paulburton@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        "David S . Miller" <davem@...emloft.net>,
        Borislav Petkov <bp@...en8.de>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Andy Lutomirski <luto@...nel.org>,
        Ralf Baechle <ralf@...ux-mips.org>,
        Ingo Molnar <mingo@...hat.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Russell King <linux@...linux.org.uk>
Subject: Re: [PATCH 5/5] arm64: Remove TIF_NOHZ

On Fri, Feb 14, 2020 at 04:26:15PM +0100, Frederic Weisbecker wrote:
> The syscall slow path is spuriously invoked when context tracking is
> activated while the entry code calls context tracking from fast path.
> 
> Remove that overhead and the unused flag itself while at it.
> 
> Signed-off-by: Frederic Weisbecker <frederic@...nel.org>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Borislav Petkov <bp@...en8.de>
> Cc: Catalin Marinas <catalin.marinas@....com>
> Cc: Will Deacon <will@...nel.org>
> ---
>  arch/arm64/Kconfig                   | 1 -
>  arch/arm64/include/asm/thread_info.h | 4 +---
>  2 files changed, 1 insertion(+), 4 deletions(-)

Acked-by: Will Deacon <will@...nel.org>

Do you want this to go via the arm64 tree? It looks like it makes sense
on its own to me, so I could pick it as a fix.

Will