From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755351AbdCJUX5 (ORCPT ); Fri, 10 Mar 2017 15:23:57 -0500 Received: from Galois.linutronix.de ([146.0.238.70]:59725 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755176AbdCJUXs (ORCPT ); Fri, 10 Mar 2017 15:23:48 -0500 Date: Fri, 10 Mar 2017 21:23:43 +0100 (CET) From: Thomas Gleixner To: Kyle Huey cc: LKML , Peter Zijlstra , Andy Lutomirski , "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" Subject: Re: [PATCH v2 0/3] x86/process: Optimize __switch_to_xtra() In-Reply-To: Message-ID: References: <20170214081104.9244-1-khuey@kylehuey.com> User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 8 Mar 2017, Kyle Huey wrote: > On Tue, Feb 28, 2017 at 10:33 AM, Kyle Huey wrote: > > On Tue, Feb 14, 2017 at 12:11 AM, Kyle Huey wrote: > >> GCC generates lousy code in __switch_to_xtra. This patch series is an > >> updated version of tglx's patches from last year > >> (https://lkml.org/lkml/2016/12/15/432) that address review comments. > >> > >> Since v1: > >> Part 1 - x86/process: Optimize TIF checks in __switch_to_xtra() > >> - READ_ONCE annotations added as requested by Andy Lutomirski > >> > >> Part 2 - x86/process: Correct and optimize TIF_BLOCKSTEP switch > >> - DEBUGCTLMSR_BTF is now modified when either the previous or > >> next or both tasks use it, because the MSR is "highly magical". > >> > >> Part 3 - x86/process: Optimize TIF_NOTSC switch > >> - Unchanged > >> > >> I didn't introduce a cpufeature for blockstep because that would > >> add additional overhead compared to the existing code, where it's > >> generally known at compile time that blockstep is supported. Perhaps > >> we should just BUG_ON(!arch_has_block_step()) here if we really > >> care to check anything. > >> > >> arch/x86/include/asm/msr-index.h | 1 + > >> arch/x86/include/asm/tlbflush.h | 10 ++++++++++ > >> arch/x86/kernel/process.c | 76 +++++++++++++++++++++++++++++++++++----------------------------------------- > >> 3 files changed, 46 insertions(+), 41 deletions(-) > >> > > > > Has anyone had a change to look at these? > > Maybe now that the 4.11 merge window is closed? :) Yes. It's on my radar, but I'm swamped with regressions. Next week should be more time for that. Thanks, tglx