From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 764FAC4332F for ; Fri, 7 Jan 2022 07:25:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235139AbiAGHZO (ORCPT ); Fri, 7 Jan 2022 02:25:14 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33074 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235039AbiAGHZM (ORCPT ); Fri, 7 Jan 2022 02:25:12 -0500 Received: from mail-io1-xd2b.google.com (mail-io1-xd2b.google.com [IPv6:2607:f8b0:4864:20::d2b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9C652C061201 for ; Thu, 6 Jan 2022 23:25:12 -0800 (PST) Received: by mail-io1-xd2b.google.com with SMTP id y18so6076955iob.8 for ; Thu, 06 Jan 2022 23:25:12 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=Dt5wFTIivnEVZNJ35QfigYoIPkloAu9LxIwiM8cfNlM=; b=KEUgoAw/F9G/n+DL3vPDPzqUuCnfnBzCRczFO16S99KbAcoAyrV9Vpb2AD74ahCjh8 uf8VigJL/FmZUKO+jofCVvFOHZuM7q+xtWDz53MAO4BA0Mn2zHV0OH6UxkAKRJl5TaAY SUMPxqRnmW04h8A9GnZu7raeMdpapoBAMIqGKj4vLsfHIqnGc4ROdp9a0I4kXG2ahw9d XRUltLOLGcfkj+RMWNT+3kyWS7LdregbHr/zh8eNY6EorURFTH4Egx1INGlForVlX1BH p2w0dBHu+Ap8teOi/dGdqzp8u93hW6oyVDaMJTA4hopr+3AasJCRGO7TSKgwVQ4jSC74 LOgA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=Dt5wFTIivnEVZNJ35QfigYoIPkloAu9LxIwiM8cfNlM=; b=R6E521im32dFumL0GadjY6F1OoQTeI8lLzy+G8uIapXTHC9+LXr3Ispc7tetSS6bQd lPAxmEIQY4w57fuMrumYqX04Zjqa35aR3HnqJ63Onmzj/1yrWuzcBwIouDnwgoxSLNb0 nUw+7tYG0Pk0X4C54ktcSXChWpK0XIu/uatQ6gUmzd8SuD9x4gYgWukmMEXT8f+IcS9g mVSMGN3jCBquZXSVzjW7Ckce+R/LeGHEi1Z+O53KEwT1Gd4i8yvAPe/i0C+Ner0lFkEI 6OtZ3qdxLGa+MVDZy/x/zGuxXZgphEVoJiGjtVWynLdkJavcW25GYG7i6/91KpJjC/C5 5zbA== X-Gm-Message-State: AOAM531WnYAoqs7Kg59Z7+lQp6NuWZQd4rL9y3GkL0Y5Llx+nybtkG0w Oopge4O5fM5hP43R8J112pWPbw== X-Google-Smtp-Source: ABdhPJz3x1HWzD5i0AVExGboPsVu371NgLICgXvka4rbxX4XJLCTLcI+ZJ0R+n6BnSvFqM8bGhULrw== X-Received: by 2002:a5e:9905:: with SMTP id t5mr26785346ioj.16.1641540311737; Thu, 06 Jan 2022 23:25:11 -0800 (PST) Received: from google.com ([2620:15c:183:200:2e0a:5e5e:fac:e07b]) by smtp.gmail.com with ESMTPSA id g1sm2528097ila.26.2022.01.06.23.25.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 06 Jan 2022 23:25:11 -0800 (PST) Date: Fri, 7 Jan 2022 00:25:07 -0700 From: Yu Zhao To: Will Deacon Cc: Andrew Morton , Linus Torvalds , Andi Kleen , Catalin Marinas , Dave Hansen , Hillf Danton , Jens Axboe , Jesse Barnes , Johannes Weiner , Jonathan Corbet , Matthew Wilcox , Mel Gorman , Michael Larabel , Michal Hocko , Rik van Riel , Vlastimil Babka , Ying Huang , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, page-reclaim@google.com, x86@kernel.org, Konstantin Kharlamov Subject: Re: [PATCH v6 1/9] mm: x86, arm64: add arch_has_hw_pte_young() Message-ID: References: <20220104202227.2903605-1-yuzhao@google.com> <20220104202227.2903605-2-yuzhao@google.com> <20220105104526.GA3015@willie-the-truck> <20220106103009.GA4420@willie-the-truck> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220106103009.GA4420@willie-the-truck> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 06, 2022 at 10:30:09AM +0000, Will Deacon wrote: > On Wed, Jan 05, 2022 at 01:47:08PM -0700, Yu Zhao wrote: > > On Wed, Jan 05, 2022 at 10:45:26AM +0000, Will Deacon wrote: > > > On Tue, Jan 04, 2022 at 01:22:20PM -0700, Yu Zhao wrote: > > > > diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps > > > > index 870c39537dd0..56e4ef5d95fa 100644 > > > > --- a/arch/arm64/tools/cpucaps > > > > +++ b/arch/arm64/tools/cpucaps > > > > @@ -36,6 +36,7 @@ HAS_STAGE2_FWB > > > > HAS_SYSREG_GIC_CPUIF > > > > HAS_TLB_RANGE > > > > HAS_VIRT_HOST_EXTN > > > > +HW_AF > > > > HW_DBM > > > > KVM_PROTECTED_MODE > > > > MISMATCHED_CACHE_TYPE > > > > > > As discussed in the previous threads, we really don't need the complexity > > > of the additional cap for the arm64 part. Please can you just use the > > > existing code instead? It's both simpler and, as you say, it's equivalent > > > for existing hardware. > > > > > > That way, this patch just ends up being a renaming exercise and we're all > > > good. > > > > No, renaming alone isn't enough. A caller needs to disable preemption > > before calling system_has_hw_af(), and I don't think it's reasonable > > to ask this caller to do it on x86 as well. > > > > It seems you really prefer not to have HW_AF. So the best I can > > accommodate, considering other potential archs, e.g., risc-v (I do > > plan to provide benchmark results on risc-v, btw), is: > > > > static inline bool arch_has_hw_pte_young(bool local) > > { > > bool hw_af; > > > > if (local) { > > WARN_ON(preemptible()); > > return cpu_has_hw_af(); > > } > > > > preempt_disable(); > > hw_af = system_has_hw_af(); > > preempt_enable(); > > > > return hw_af; > > } > > > > Or please give me something else I can call without disabling > > preemption, sounds good? > > Sure thing, let me take a look. Do you have your series on a public git > tree someplace? Thanks! This patch (updated) on Gerrit: https://linux-mm-review.googlesource.com/c/page-reclaim/+/1500/1 And the entire series: git fetch https://linux-mm.googlesource.com/page-reclaim refs/changes/08/1508/1