From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752418AbdLDWwb (ORCPT ); Mon, 4 Dec 2017 17:52:31 -0500 Received: from merlin.infradead.org ([205.233.59.134]:55474 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752075AbdLDWwa (ORCPT ); Mon, 4 Dec 2017 17:52:30 -0500 Date: Mon, 4 Dec 2017 23:51:44 +0100 From: Peter Zijlstra To: Andy Lutomirski Cc: Thomas Gleixner , LKML , X86 ML , Linus Torvalds , Dave Hansen , Borislav Petkov , Greg KH , Kees Cook , Hugh Dickins , Brian Gerst , Josh Poimboeuf , Denys Vlasenko , Rik van Riel , Boris Ostrovsky , Juergen Gross , David Laight , Eduardo Valentin , aliguori@amazon.com, Will Deacon , Daniel Gruss , Dave Hansen Subject: Re: [patch 55/60] x86/mm: Use INVPCID for __native_flush_tlb_single() Message-ID: <20171204225144.GD20227@worktop.programming.kicks-ass.net> References: <20171204140706.296109558@linutronix.de> <20171204150609.338279526@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.22.1 (2013-10-16) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 04, 2017 at 02:25:43PM -0800, Andy Lutomirski wrote: > On Mon, Dec 4, 2017 at 6:08 AM, Thomas Gleixner wrote: > > From: Dave Hansen > > > > This uses INVPCID to shoot down individual lines of the user mapping > > instead of marking the entire user map as invalid. This > > could/might/possibly be faster. > > > > This for sure needs tlb_single_page_flush_ceiling to be redetermined; > > esp. since INVPCID is _slow_. > > I'm wondering if INVPCID is *so* slow that this patch is entirely > counterproductive. We should find some of the benchmarks that were used to determine tlb_single_page_flush_ceiling and measure. I've not gotten around to doing either. Someone called Dave Hansen did that patch and might still have something lying around to help with that: a5102476a24b ("x86/mm: Set TLB flush tunable to sane value (33)")