linux/arch/x86/mm
Fenghua Yu 1db491f77b x86/mm: Reduce PAE-mode per task pgd allocation overhead from 4K to 32 bytes
With more embedded systems emerging using Quark, among other
things, 32-bit kernel matters again. 32-bit machine and kernel
uses PAE paging, which currently wastes at least 4K of memory
per process on Linux where we have to reserve an entire page to
support a single 32-byte PGD structure. It would be a very good
thing if we could eliminate that wastage.

PAE paging is used to access more than 4GB memory on x86-32. And
it is required for NX.

In this patch, we still allocate one page for pgd for a Xen
domain and 64-bit kernel because one page pgd is assumed in
these cases. But we can save memory space by only allocating
32-byte pgd for 32-bit PAE kernel when it is not running as a
Xen domain.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Glenn Williamson <glenn.p.williamson@intel.com>
Cc: H. Peter Anvin <hpa@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1421382601-46912-1-git-send-email-fenghua.yu@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-02-19 01:28:38 +01:00
..
kmemcheck x86: Replace __get_cpu_var uses 2014-08-26 13:45:49 -04:00
amdtopology.c
dump_pagetables.c Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-12-10 13:59:34 -08:00
extable.c
fault.c vm: add VM_FAULT_SIGSEGV handling support 2015-01-29 10:51:32 -08:00
gup.c x86/gup: Replace ACCESS_ONCE with READ_ONCE 2014-12-18 09:54:38 +01:00
highmem_32.c mm: accurately calculate zone->managed_pages for highmem zones 2013-07-03 16:07:33 -07:00
hugetlbpage.c hugetlb: restrict hugepage_migration_support() to x86_64 2014-06-04 16:53:51 -07:00
init_32.c x86: remove the Xen-specific _PAGE_IOMAP PTE flag 2014-09-23 13:36:20 +00:00
init_64.c Merge branch 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-12-10 14:24:20 -08:00
init.c x86, mm: Change cachemode exports to non-gpl 2015-01-22 21:50:14 +01:00
iomap_32.c x86: Use new cache mode type in mm/iomap_32.c 2014-11-16 11:04:25 +01:00
ioremap.c Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-12-10 13:59:34 -08:00
kmmio.c x86: Delete non-required instances of include <linux/init.h> 2014-01-06 21:25:18 -08:00
Makefile x86, mpx: Add MPX-specific mmap interface 2014-11-18 00:58:53 +01:00
memtest.c x86/mm: memblock: switch to use NUMA_NO_NODE 2014-01-21 16:19:47 -08:00
mm_internal.h x86: Enable PAT to use cache mode translation tables 2014-11-16 11:04:26 +01:00
mmap.c x86/mm: Apply the section attribute to the variable, not its type 2014-09-09 07:13:39 +02:00
mmio-mod.c x86: delete __cpuinit usage from all x86 files 2013-07-14 19:36:56 -04:00
mpx.c x86, mpx: Explicitly disable 32-bit MPX support on 64-bit kernels 2015-01-22 21:11:06 +01:00
numa_32.c x86: Fix the initialization of physnode_map 2014-02-01 22:15:51 -08:00
numa_64.c
numa_emulation.c x86: delete __cpuinit usage from all x86 files 2013-07-14 19:36:56 -04:00
numa_internal.h
numa.c Merge branch 'akpm' (patches from Andrew Morton) 2014-10-14 03:54:50 +02:00
pageattr-test.c x86: define _PAGE_NUMA by reusing software bits on the PMD and PTE levels 2014-06-04 16:53:55 -07:00
pageattr.c xen: additional features for 3.19-rc0 2014-12-16 13:23:03 -08:00
pat_internal.h x86: Use new cache mode type in memtype related functions 2014-11-16 11:04:26 +01:00
pat_rbtree.c x86: Use new cache mode type in memtype related functions 2014-11-16 11:04:26 +01:00
pat.c x86: Don't rely on VMWare emulating PAT MSR correctly 2015-01-20 14:33:45 +01:00
pf_in.c
pf_in.h
pgtable_32.c x86: Remove set_pmd_pfn 2014-09-01 10:15:31 +02:00
pgtable.c x86/mm: Reduce PAE-mode per task pgd allocation overhead from 4K to 32 bytes 2015-02-19 01:28:38 +01:00
physaddr.c
physaddr.h
setup_nx.c x86: delete __cpuinit usage from all x86 files 2013-07-14 19:36:56 -04:00
srat.c x86/mm: Avoid duplicated pxm_to_node() calls 2014-02-09 15:32:31 +01:00
testmmiotrace.c
tlb.c x86/mm: Fix sparse 'tlb_single_page_flush_ceiling' warning and make the variable read-mostly 2014-08-10 09:07:18 +02:00