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 X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 97965C282D8 for ; Fri, 1 Feb 2019 16:16:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7054D21726 for ; Fri, 1 Feb 2019 16:16:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730580AbfBAQQz (ORCPT ); Fri, 1 Feb 2019 11:16:55 -0500 Received: from mga12.intel.com ([192.55.52.136]:34101 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726582AbfBAQQz (ORCPT ); Fri, 1 Feb 2019 11:16:55 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga106.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 01 Feb 2019 08:16:54 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,549,1539673200"; d="scan'208";a="114532242" Received: from linux.intel.com ([10.54.29.200]) by orsmga008.jf.intel.com with ESMTP; 01 Feb 2019 08:16:54 -0800 Received: from [10.254.84.202] (kliang2-mobl1.ccr.corp.intel.com [10.254.84.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by linux.intel.com (Postfix) with ESMTPS id 348615804BB; Fri, 1 Feb 2019 08:16:53 -0800 (PST) Subject: Re: [PATCH V4 01/13] perf/core, x86: Add PERF_SAMPLE_DATA_PAGE_SIZE To: Peter Zijlstra , "Kirill A. Shutemov" Cc: acme@kernel.org, tglx@linutronix.de, mingo@redhat.com, linux-kernel@vger.kernel.org, eranian@google.com, jolsa@redhat.com, namhyung@kernel.org, ak@linux.intel.com, luto@amacapital.net, Vlastimil Babka , Will Deacon References: <1548966486-49963-1-git-send-email-kan.liang@linux.intel.com> <20190201092240.GB31498@hirez.programming.kicks-ass.net> <20190201100358.GD31552@hirez.programming.kicks-ass.net> <20190201103600.uflrwzgwj2tadhey@kshutemo-mobl1> <20190201124348.GC31534@hirez.programming.kicks-ass.net> From: "Liang, Kan" Message-ID: <9fbb7bd3-b150-1ed1-bf03-c44d789172d0@linux.intel.com> Date: Fri, 1 Feb 2019 11:16:51 -0500 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.5.0 MIME-Version: 1.0 In-Reply-To: <20190201124348.GC31534@hirez.programming.kicks-ass.net> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2/1/2019 7:43 AM, Peter Zijlstra wrote: > On Fri, Feb 01, 2019 at 01:36:00PM +0300, Kirill A. Shutemov wrote: >> On Fri, Feb 01, 2019 at 11:03:58AM +0100, Peter Zijlstra wrote: > >>> Will just mentioned a lovely feature where some archs have multi entry >>> large pages. >>> >>> Possible something like: >>> >>> if (pud_large(*pud)) { >>> struct page *page = pud_page(*pud); >>> int order = PUD_SHIFT; >>> >>> if (PageHuge(page)) { >>> page = compound_head(page); >>> order += compound_order(page); >>> } >>> >>> return 1ULL << order; >>> } >>> >>> works correctly. >> >> For more fun: some compound pages can be mapped withe page table entries >> not matching it's compound size, i.e. 2M pages mapped with PTE. > > Surely not for PageHuge() ?! I thought the point of hugetlbfs was to > guarantee page granularity. > > How is the below? > > static u64 __perf_get_page_size(struct mm_struct *mm, unsigned long addr) > { > pgd_t *pgd; > p4d_t *p4d; > pud_t *pud; > pmd_t *pmd; > pte_t *pte; > > pgd = pgd_offset(mm, addr); > if (pgd_none(*pgd)) > return 0; > > p4d = p4d_offset(pgd, addr); > if (!p4d_present(*p4d)) > return 0; > > if (p4d_large(*p4d)) { This one looks like x86 specific? Kan > struct page *page = p4d_page(*p4d); > int shift = P4D_SHIFT; > > if (PageHuge(page)) { > page = compound_head(page); > shift = PAGE_SHIFT + compound_order(page); > } > > return 1ULL << shift; > } > > if (!p4d_present(*p4d)) > return 0; > > pud = pud_offset(p4d, addr); > if (!pud_present(*pud)) > return 0; > > if (pud_large(*pud)) { > struct page *page = pud_page(*pud); > int shift = P4D_SHIFT; > > if (PageHuge(page)) { > page = compound_head(page); > shift = PAGE_SHIFT + compound_order(page); > } > > return 1ULL << shift; > } > > pmd = pmd_offset(pud, addr); > if (!pmd_present(*pmd)) > return 0; > > if (pmd_large(*pmd)) { > struct page *page = pud_page(*pud); > int shift = P4D_SHIFT; > > if (PageHuge(page)) { > page = compound_head(page); > shift = PAGE_SHIFT + compound_order(page); > } > > return 1ULL << shift; > } > > pte = pte_offset_map(pmd, addr); > if (!pte_present(*pte)) { > pte_unmap(pte); > return 0; > } > > pte_unmap(pte); > return PAGE_SIZE; > } >