From mboxrd@z Thu Jan 1 00:00:00 1970 From: Frederic Weisbecker Subject: Re: [patch V2 09/17] x86/entry: Remove _TIF_NOHZ from _TIF_WORK_SYSCALL_ENTRY Date: Mon, 6 Jan 2020 05:11:25 +0100 Message-ID: <20200106041124.GA26097@lenoir> References: <20191023122705.198339581@linutronix.de> <20191023123118.491328859@linutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20191023123118.491328859@linutronix.de> Sender: linux-kernel-owner@vger.kernel.org To: Thomas Gleixner Cc: LKML , x86@kernel.org, Peter Zijlstra , Andy Lutomirski , Will Deacon , Paolo Bonzini , kvm@vger.kernel.org, linux-arch@vger.kernel.org, Mike Rapoport , Josh Poimboeuf , Miroslav Benes List-Id: linux-arch.vger.kernel.org On Wed, Oct 23, 2019 at 02:27:14PM +0200, Thomas Gleixner wrote: > From: Thomas Gleixner > > Evaluating _TIF_NOHZ to decide whether to use the slow syscall entry path > is not only pointless, it's actually counterproductive: > > 1) Context tracking code is invoked unconditionally before that flag is > evaluated. > > 2) If the flag is set the slow path is invoked for nothing due to #1 > > Remove it. > > Signed-off-by: Thomas Gleixner I'm borrowing this patch for a series of mine. But if you apply it in the meantime, that would be even better :-) Thanks! From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:54602 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727432AbgAFEL2 (ORCPT ); Sun, 5 Jan 2020 23:11:28 -0500 Date: Mon, 6 Jan 2020 05:11:25 +0100 From: Frederic Weisbecker Subject: Re: [patch V2 09/17] x86/entry: Remove _TIF_NOHZ from _TIF_WORK_SYSCALL_ENTRY Message-ID: <20200106041124.GA26097@lenoir> References: <20191023122705.198339581@linutronix.de> <20191023123118.491328859@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191023123118.491328859@linutronix.de> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Thomas Gleixner Cc: LKML , x86@kernel.org, Peter Zijlstra , Andy Lutomirski , Will Deacon , Paolo Bonzini , kvm@vger.kernel.org, linux-arch@vger.kernel.org, Mike Rapoport , Josh Poimboeuf , Miroslav Benes Message-ID: <20200106041125.N1S5nME4crqck_AWSPxR4lXBWGsnrY-y2uAFITPjHJ8@z> On Wed, Oct 23, 2019 at 02:27:14PM +0200, Thomas Gleixner wrote: > From: Thomas Gleixner > > Evaluating _TIF_NOHZ to decide whether to use the slow syscall entry path > is not only pointless, it's actually counterproductive: > > 1) Context tracking code is invoked unconditionally before that flag is > evaluated. > > 2) If the flag is set the slow path is invoked for nothing due to #1 > > Remove it. > > Signed-off-by: Thomas Gleixner I'm borrowing this patch for a series of mine. But if you apply it in the meantime, that would be even better :-) Thanks!