From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-f71.google.com (mail-oi0-f71.google.com [209.85.218.71]) by kanga.kvack.org (Postfix) with ESMTP id BE4276B0292 for ; Tue, 18 Jul 2017 13:06:39 -0400 (EDT) Received: by mail-oi0-f71.google.com with SMTP id 191so1832841oii.4 for ; Tue, 18 Jul 2017 10:06:39 -0700 (PDT) Received: from mail.kernel.org (mail.kernel.org. [198.145.29.99]) by mx.google.com with ESMTPS id k27si2362013oiy.376.2017.07.18.10.06.37 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 18 Jul 2017 10:06:38 -0700 (PDT) Received: from mail-ua0-f182.google.com (mail-ua0-f182.google.com [209.85.217.182]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 38BE923693 for ; Tue, 18 Jul 2017 17:06:37 +0000 (UTC) Received: by mail-ua0-f182.google.com with SMTP id y47so15958321uag.0 for ; Tue, 18 Jul 2017 10:06:37 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20170718085341.nlt35dph4oukb4tc@gmail.com> References: <20170705121807.GF4941@worktop> <20170705170219.ogjnswef3ufgeklz@hirez.programming.kicks-ass.net> <20170718085341.nlt35dph4oukb4tc@gmail.com> From: Andy Lutomirski Date: Tue, 18 Jul 2017 10:06:15 -0700 Message-ID: Subject: Re: [PATCH v4 10/10] x86/mm: Try to preserve old TLB entries using PCID Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-mm@kvack.org List-ID: To: Ingo Molnar Cc: Peter Zijlstra , Andy Lutomirski , X86 ML , "linux-kernel@vger.kernel.org" , Borislav Petkov , Linus Torvalds , Andrew Morton , Mel Gorman , "linux-mm@kvack.org" , Nadav Amit , Rik van Riel , Dave Hansen , Arjan van de Ven On Tue, Jul 18, 2017 at 1:53 AM, Ingo Molnar wrote: > > * Peter Zijlstra wrote: > >> On Wed, Jul 05, 2017 at 09:04:39AM -0700, Andy Lutomirski wrote: >> > On Wed, Jul 5, 2017 at 5:18 AM, Peter Zijlstra wrote: >> > > On Thu, Jun 29, 2017 at 08:53:22AM -0700, Andy Lutomirski wrote: >> > >> @@ -104,18 +140,20 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next, >> > >> >> > >> /* Resume remote flushes and then read tlb_gen. */ >> > >> cpumask_set_cpu(cpu, mm_cpumask(next)); >> > > >> > > Barriers should have a comment... what is being ordered here against >> > > what? >> > >> > How's this comment? >> > >> > /* >> > * Resume remote flushes and then read tlb_gen. We need to do >> > * it in this order: any inc_mm_tlb_gen() caller that writes a >> > * larger tlb_gen than we read here must see our cpu set in >> > * mm_cpumask() so that it will know to flush us. The barrier >> > * here synchronizes with inc_mm_tlb_gen(). >> > */ >> >> Slightly confusing, you mean this, right? >> >> >> cpumask_set_cpu(cpu, mm_cpumask()); inc_mm_tlb_gen(); >> >> MB MB >> >> next_tlb_gen = atomic64_read(&next->context.tlb_gen); flush_tlb_others(mm_cpumask()); >> >> >> which seems to make sense. > > Btw., I'll wait for a v5 iteration before applying this last patch to tip:x86/mm. I'll send it shortly. I think I'll also add a patch to factor out the flush calls a bit more to prepare for Mel's upcoming fix. > > Thanks, > > Ingo -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org