From: Christoph Lameter <clameter@sgi.com>
To: akpm@linux-foundation.org
Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
Martin Bligh <mbligh@google.com>,
linux-mm@kvack.org, Andi Kleen <ak@suse.de>,
Christoph Lameter <clameter@sgi.com>,
Dave Hansen <hansendc@us.ibm.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Subject: [PATCH 2/3] x86_64: Implement SPARSE_VIRTUAL
Date: Mon, 2 Apr 2007 17:38:43 -0700 (PDT) [thread overview]
Message-ID: <20070403003843.829.50704.sendpatchset@schroedinger.engr.sgi.com> (raw)
In-Reply-To: <20070403003837.829.31019.sendpatchset@schroedinger.engr.sgi.com>
x86_64 implement SPARSE_VIRTUAL
x86_64 is using 2M page table entries to map its 1-1 kernel space.
We implement the virtual memmap also using 2M page table entries.
So there is no difference at all to FLATMEM. Both schemes require
a page table and a TLB for each 2MB. FLATMEM still references memory
since the mem_map pointer itself a variable. SPARSE_VIRTUAL uses a
constant for vmemmap. Thus no memory reference. SPARSE_VIRTUAL should
be superior to even FLATMEM.
With this SPARSEMEM becomes the most efficient way of handling
virt_to_page, pfn_to_page and friends for UP, SMP and NUMA on
x86_64.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Index: linux-2.6.21-rc5-mm3/include/asm-x86_64/page.h
===================================================================
--- linux-2.6.21-rc5-mm3.orig/include/asm-x86_64/page.h 2007-04-02 12:25:03.000000000 -0700
+++ linux-2.6.21-rc5-mm3/include/asm-x86_64/page.h 2007-04-02 12:27:16.000000000 -0700
@@ -127,6 +127,7 @@
VM_READ | VM_WRITE | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)
#define __HAVE_ARCH_GATE_AREA 1
+#define vmemmap ((struct page *)0xffffe20000000000UL)
#include <asm-generic/memory_model.h>
#include <asm-generic/page.h>
Index: linux-2.6.21-rc5-mm3/Documentation/x86_64/mm.txt
===================================================================
--- linux-2.6.21-rc5-mm3.orig/Documentation/x86_64/mm.txt 2007-04-02 12:25:03.000000000 -0700
+++ linux-2.6.21-rc5-mm3/Documentation/x86_64/mm.txt 2007-04-02 12:27:16.000000000 -0700
@@ -9,6 +9,7 @@
ffff810000000000 - ffffc0ffffffffff (=46 bits) direct mapping of all phys. memory
ffffc10000000000 - ffffc1ffffffffff (=40 bits) hole
ffffc20000000000 - ffffe1ffffffffff (=45 bits) vmalloc/ioremap space
+ffffe20000000000 - ffffe2ffffffffff (=40 bits) virtual memory map
... unused hole ...
ffffffff80000000 - ffffffff82800000 (=40 MB) kernel text mapping, from phys 0
... unused hole ...
Index: linux-2.6.21-rc5-mm3/arch/x86_64/Kconfig
===================================================================
--- linux-2.6.21-rc5-mm3.orig/arch/x86_64/Kconfig 2007-04-02 12:27:13.000000000 -0700
+++ linux-2.6.21-rc5-mm3/arch/x86_64/Kconfig 2007-04-02 12:28:13.000000000 -0700
@@ -392,6 +392,12 @@
def_bool y
depends on (NUMA || EXPERIMENTAL)
+config SPARSE_VIRTUAL
+ def_bool y
+
+config ARCH_SUPPORTS_PMD_MAPPING
+ def_bool y
+
config ARCH_MEMORY_PROBE
def_bool y
depends on MEMORY_HOTPLUG
--
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next prev parent reply other threads:[~2007-04-03 0:38 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-04-03 0:38 [PATCH 1/1] Generic Virtual Memmap suport for SPARSEMEM V2 Christoph Lameter
2007-04-03 0:38 ` Christoph Lameter [this message]
2007-04-03 0:38 ` [PATCH 3/3] IA64: Implement SPARSE_VIRTUAL Christoph Lameter
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