From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754201AbdJISIN (ORCPT ); Mon, 9 Oct 2017 14:08:13 -0400 Received: from mail.skyhub.de ([5.9.137.197]:54178 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752001AbdJISIM (ORCPT ); Mon, 9 Oct 2017 14:08:12 -0400 Date: Mon, 9 Oct 2017 20:08:10 +0200 From: Borislav Petkov To: Andy Lutomirski Cc: X86 ML , "linux-kernel@vger.kernel.org" , Markus Trippelsdorf , Adam Borowski , Brian Gerst , Johannes Hirte Subject: Re: [RFC PATCH] x86/mm: Flush more aggressively in lazy TLB mode Message-ID: <20171009180810.zkcugzxicgpsegh3@pd.tnic> References: <8eccc9240041ea7cb94624cab8d07e2a6e911ba7.1507567665.git.luto@kernel.org> <20171009170231.fkpraqokz6e4zeco@pd.tnic> <20171009173651.3gsh3k252jnase7o@pd.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 09, 2017 at 10:50:34AM -0700, Andy Lutomirski wrote: > The choices are somewhat lazy and not lazy at all. Yeah, you probably should explain those choices somewhere and what exactly they mean. > The degree of simplification I would get by removing it is basically > nil. The debugfs code itself goes away, and a > static_branch_unlikely() turns into a static_cpu_has(), and that's it. Sure. But it is one variable less which is not really needed by the widest audience. > The real reason I added it is because Chris Mason volunteered to > benchmark it, and I'll send it to him once it survives a bit of > review. Sure but it still doesn't need to be upstream. You can do all the measurements with a patch ontop. You don't need the permanent knob in debugfs either. After a year, no one would really need that anymore, since the majority will be PCID machines. > This is non-lazy. It's roughtly what our state was in old kernels > when we went lazy and then called leave_mm(). non-lazy when we went lazy?! Now I'm confused :) -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.