Transparent Huge Pages - Revision history

Daney: /* Page Table Structure */

2012-09-27T15:08:54Z

‎Page Table Structure

2012-09-27T14:59:20Z

‎Size of Huge Pages

2012-09-27T14:40:59Z

‎See also

2012-09-27T12:15:12Z

‎See also

2012-09-27T11:41:32Z

2012-09-27T11:39:17Z

‎Size of Huge Pages

2012-09-27T11:04:38Z

2012-09-27T09:47:52Z

2012-09-26T17:48:59Z

2012-09-26T16:02:46Z

@@ Line 28: / Line 28: @@
 {|
 |-
-|[[File:MIPS_page_table_64bit_normal_tlb.svg|600px|thumb|right|Standard 4K pages on a 64-bit kernel]]
+|[[File:MIPS_page_table_64bit_normal_tlb.svg|600px|thumb|right|Standard 4K pages on a 64-bit kernel, each PTE entry corresponds to a single EntryLo0 or EntryLo1 value, the standard pages have a size specified by PageMask]]
 |-
-|[[File:MIPS_page_table_64bit_huge_tlb.svg|600px|thumb|right|2M Huge Pages on a 64-bit kernel]]
+|[[File:MIPS_page_table_64bit_huge_tlb.svg|600px|thumb|right|2M Huge Pages on a 64-bit kernel, each PAGE_HUGE PMD entry corresponds to an (EntryLo0,EntryLo1) pair, so the PAGE_HUGE page has a size twice that indicated by PageMask]]
 |}

@@ Line 5: / Line 5: @@
 == Size of Huge Pages ==
-Due to the page table layout doubling the base page size means the huge page size will increase by a factor of 8.  These are the numbers:
+Due to the page table layout doubling the base page size means the huge page size will increase by a factor of 4.  These are the numbers:
 {| {{PrettyTable}}
 ! Base Page Size !! Huge Page Size !! Size of pgd !! Size of pmd and pte !! Address space !! Comments

@@ Line 36: / Line 36: @@
 == See also ==
-* [[Page_size]]
+* [[Page size]]
 * http://www.stanford.edu/class/cs240/readings/navarro.pdf “Practical, transparent operating system support for superpages”

← Older revision		Revision as of 12:15, 27 September 2012
Line 36:		Line 36:

	== See also ==		== See also ==
		+	* [[Page_size]]
	* http://www.stanford.edu/class/cs240/readings/navarro.pdf “Practical, transparent operating system support for superpages”		* http://www.stanford.edu/class/cs240/readings/navarro.pdf “Practical, transparent operating system support for superpages”

@@ Line 7: / Line 7: @@
 Due to the page table layout doubling the base page size means the huge page size will increase by a factor of 8.  These are the numbers:
 {| {{PrettyTable}}
-! Base Page Size !! Huge Page Size !! size of pgd !! size of pmd and pte !! Address space !! Comments
+! Base Page Size !! Huge Page Size !! Size of pgd !! Size of pmd and pte !! Address space !! Comments
 |-
 | 4kB || 2MB || 8kB || 4kB || 40
@@ Line 28: / Line 28: @@
 {|
 |-
-|[[File:MIPS_page_table_64bit_normal_tlb.svg|500px|thumb|right|Standard 4K pages on a 64-bit kernel]]
+|[[File:MIPS_page_table_64bit_normal_tlb.svg|600px|thumb|right|Standard 4K pages on a 64-bit kernel]]
-|[[File:MIPS_page_table_64bit_huge_tlb.svg|500px|thumb|right|2M Huge Pages on a 64-bit kernel]]
+|-
 |}

@@ Line 7: / Line 7: @@
 Due to the page table layout doubling the base page size means the huge page size will increase by a factor of 8.  These are the numbers:
 {| {{PrettyTable}}
-! Base Page Size !! Huge Page Size !! Comments
+! Base Page Size !! Huge Page Size !! size of pgd !! size of pmd and pte !! Address space !! Comments
 |-
-| 4kB || 2MB
+| 4kB || 2MB || 8kB || 4kB || 40
 |-
-| 8kB || 8MB || R8000 and Cavium cnMIPS cores only
+| 8kB || 8MB || 8kB || 8kB || 43 || R8000 and Cavium cnMIPS cores only
 |-
-| 16kB || 32MB
+| 16kB || 32MB || 16kB || 16kB || 46
 |-
-| 32kB || 128MB || Cavium cnMIPS cores only
+| 32kB || 128MB || 32kB || 32kB || 49 || Cavium cnMIPS cores only
 |-
-| 64kB || 512MB
+| 64kB || 512MB || 64kB || 64kB || 52
 |}

@@ Line 22: / Line 22: @@
 Only the very largest systems will gain from enabling huge page support with a very large base page size.
-== Page Table Layout ==
+== Page Table Structure ==
-[[File:MIPS_page_table_64bit_normal_tlb.svg|200px|thumb|right|Standard 4K pages on a 64-bit kernel]]
+Similar to what x86 does MIPS also folds the 2MB ptes into the PMD thus eleminating the last level of the page table.
-[[File:MIPS_page_table_64bit_huge_tlb.svg|200px|thumb|right|2M Huge Pages on a 64-bit kernel]]
 == See also ==
 * http://www.stanford.edu/class/cs240/readings/navarro.pdf “Practical, transparent operating system support for superpages”

← Older revision		Revision as of 17:48, 26 September 2012
Line 21:		Line 21:

	Only the very largest systems will gain from enabling huge page support with a very large base page size.		Only the very largest systems will gain from enabling huge page support with a very large base page size.
		+
		+	== See also ==
		+	* http://www.stanford.edu/class/cs240/readings/navarro.pdf “Practical, transparent operating system support for superpages”