[RFC,v2,13/21] x86/pgtable: dont check PMD accessed bit

Message ID	20181226133351.828074959@intel.com (mailing list archive)
State	New, archived
Headers	show Return-Path: <owner-linux-mm@kvack.org> Received-SPF: pass (google.com: domain of fengguang.wu@intel.com designates 192.55.52.88 as permitted sender) client-ip=192.55.52.88; Message-Id: <20181226133351.828074959@intel.com> User-Agent: quilt/0.65 Date: Wed, 26 Dec 2018 21:14:59 +0800 From: Fengguang Wu <fengguang.wu@intel.com> To: Andrew Morton <akpm@linux-foundation.org> cc: Linux Memory Management List <linux-mm@kvack.org>, Jingqi Liu <jingqi.liu@intel.com>, Fengguang Wu <fengguang.wu@intel.com> cc: kvm@vger.kernel.org Cc: LKML <linux-kernel@vger.kernel.org> cc: Fan Du <fan.du@intel.com> cc: Yao Yuan <yuan.yao@intel.com> cc: Peng Dong <dongx.peng@intel.com> cc: Huang Ying <ying.huang@intel.com> cc: Dong Eddie <eddie.dong@intel.com> cc: Dave Hansen <dave.hansen@intel.com> cc: Zhang Yi <yi.z.zhang@linux.intel.com> cc: Dan Williams <dan.j.williams@intel.com> Subject: [RFC][PATCH v2 13/21] x86/pgtable: dont check PMD accessed bit References: <20181226131446.330864849@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline; filename=0006-pgtable-don-t-check-the-page-accessed-bit.patch Sender: owner-linux-mm@kvack.org Precedence: bulk
Series	PMEM NUMA node and hotness accounting/migration \| expand [RFC,v2,00/21] PMEM NUMA node and hotness accounting/migration [RFC,v2,01/21] e820: cheat PMEM as DRAM [RFC,v2,02/21] acpi/numa: memorize NUMA node type from SRAT table [RFC,v2,03/21] x86/numa_emulation: fix fake NUMA in uniform case [RFC,v2,04/21] x86/numa_emulation: pass numa node type to fake nodes [RFC,v2,05/21] mmzone: new pgdat flags for DRAM and PMEM [RFC,v2,06/21] x86,numa: update numa node type [RFC,v2,07/21] mm: export node type {pmem\|dram} under /sys/bus/node [RFC,v2,08/21] mm: introduce and export pgdat peer_node [RFC,v2,09/21] mm: avoid duplicate peer target node [RFC,v2,10/21] mm: build separate zonelist for PMEM and DRAM node [RFC,v2,11/21] kvm: allocate page table pages from DRAM [RFC,v2,12/21] x86/pgtable: allocate page table pages from DRAM [RFC,v2,13/21] x86/pgtable: dont check PMD accessed bit [RFC,v2,14/21] kvm: register in mm_struct [RFC,v2,15/21] ept-idle: EPT walk for virtual machine [RFC,v2,16/21] mm-idle: mm_walk for normal task [RFC,v2,17/21] proc: introduce /proc/PID/idle_pages [RFC,v2,18/21] kvm-ept-idle: enable module [RFC,v2,19/21] mm/migrate.c: add move_pages(MPOL_MF_SW_YOUNG) flag [RFC,v2,20/21] mm/vmscan.c: migrate anon DRAM pages to PMEM node [RFC,v2,21/21] mm/vmscan.c: shrink anon list if can migrate to PMEM

Message ID

20181226133351.828074959@intel.com (mailing list archive)

State

New, archived

Headers

Received-SPF: pass (google.com: domain of fengguang.wu@intel.com designates
 192.55.52.88 as permitted sender) client-ip=192.55.52.88;
Message-Id: <20181226133351.828074959@intel.com>
User-Agent: quilt/0.65
Date: Wed, 26 Dec 2018 21:14:59 +0800
From: Fengguang Wu <fengguang.wu@intel.com>
To: Andrew Morton <akpm@linux-foundation.org>
cc: Linux Memory Management List <linux-mm@kvack.org>,
 Jingqi Liu <jingqi.liu@intel.com>,
 Fengguang Wu <fengguang.wu@intel.com>
cc: kvm@vger.kernel.org
Cc: LKML <linux-kernel@vger.kernel.org>
cc: Fan Du <fan.du@intel.com>
cc: Yao Yuan <yuan.yao@intel.com>
cc: Peng Dong <dongx.peng@intel.com>
cc: Huang Ying <ying.huang@intel.com>
cc: Dong Eddie <eddie.dong@intel.com>
cc: Dave Hansen <dave.hansen@intel.com>
cc: Zhang Yi <yi.z.zhang@linux.intel.com>
cc: Dan Williams <dan.j.williams@intel.com>
Subject: [RFC][PATCH v2 13/21] x86/pgtable: dont check PMD accessed bit
References: <20181226131446.330864849@intel.com>
MIME-Version: 1.0
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Content-Disposition: inline;
 filename=0006-pgtable-don-t-check-the-page-accessed-bit.patch
Sender: owner-linux-mm@kvack.org
Precedence: bulk

Series

PMEM NUMA node and hotness accounting/migration | expand

Commit Message

Fengguang Wu Dec. 26, 2018, 1:14 p.m. UTC

From: Jingqi Liu <jingqi.liu@intel.com>

ept-idle will clear PMD accessed bit to speedup PTE scan -- if the bit
remains unset in the next scan, all the 512 PTEs can be skipped.

So don't complain on !_PAGE_ACCESSED in pmd_bad().

Note that clearing PMD accessed bit has its own cost, the optimization
may only be worthwhile for
- large idle area
- sparsely populated area

Signed-off-by: Jingqi Liu <jingqi.liu@intel.com>
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
---
 arch/x86/include/asm/pgtable.h |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- linux.orig/arch/x86/include/asm/pgtable.h	2018-12-23 19:50:50.917902600 +0800
+++ linux/arch/x86/include/asm/pgtable.h	2018-12-23 19:50:50.913902605 +0800
@@ -821,7 +821,8 @@  static inline pte_t *pte_offset_kernel(p
 
 static inline int pmd_bad(pmd_t pmd)
 {
-	return (pmd_flags(pmd) & ~_PAGE_USER) != _KERNPG_TABLE;
+	return (pmd_flags(pmd) & ~(_PAGE_USER | _PAGE_ACCESSED)) !=
+					(_KERNPG_TABLE & ~_PAGE_ACCESSED);
 }
 
 static inline unsigned long pages_to_mb(unsigned long npg)

[RFC,v2,13/21] x86/pgtable: dont check PMD accessed bit

Commit Message

Patch