linux-kernel - [PATCH 0/5] context_tracking: Remove TIF

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Date:   Fri, 14 Feb 2020 16:26:10 +0100
From:   Frederic Weisbecker <frederic@...nel.org>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Frederic Weisbecker <frederic@...nel.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>, Will Deacon <will@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Russell King <linux@...linux.org.uk>
Subject: [PATCH 0/5] context_tracking: Remove TIF_NOHZ from 3 archs 

TIF_NOHZ is getting deprecated by static keys which avoid to invoke
syscall slow path on every syscall. So remove that flag from
architectures that don't need it anymore (or worse yet: that spuriously
triggered syscall slow path when it's not needed anymore).

We hope to remove TIF_NOHZ entirely in the long run (PPC, MIPS, SPARC).
If we want to be able to enable/disable nohz full dynamically on runtime,
freezing all tasks and iterating through the whole tasklist to set/clear
TIF_NOHZ doesn't sound very appealing.

git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git
	arch/nohz
	
WARNING: untested on ARM 32

HEAD: 92502ebbf06ac37858694ed8f9d16fdb13ed0fe3

Thanks,
	Frederic
---

Frederic Weisbecker (4):
      context-tracking: Introduce CONFIG_HAVE_TIF_NOHZ
      x86: Remove TIF_NOHZ
      arm: Remove TIF_NOHZ
      arm64: Remove TIF_NOHZ

Thomas Gleixner (1):
      x86/entry: Remove _TIF_NOHZ from _TIF_WORK_SYSCALL_ENTRY


 arch/Kconfig                         | 16 +++++++++++-----
 arch/arm/include/asm/thread_info.h   |  1 -
 arch/arm64/include/asm/thread_info.h |  4 +---
 arch/mips/Kconfig                    |  1 +
 arch/powerpc/Kconfig                 |  1 +
 arch/sparc/Kconfig                   |  1 +
 arch/x86/include/asm/thread_info.h   | 10 ++--------
 kernel/context_tracking.c            |  2 ++
 8 files changed, 19 insertions(+), 17 deletions(-)