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SubjectRe: [PATCH] add a clear_pages function to clear pages of higher order
Changelog:
- use Kconfig and CONFIG_CLEAR_PAGES

The zeroing of a page of a arbitrary order in page_alloc.c and in hugetlb.c may benefit from a
clear_page that is capable of zeroing multiple pages at once. The following patch adds
a function "clear_pages" that is capable of clearing multiple continuous pages at once.

Patch against 2.6.11-bk6

Signed-off-by: Christoph Lameter <clameter@sgi.com>

Index: linux-2.6.11/mm/page_alloc.c
===================================================================
--- linux-2.6.11.orig/mm/page_alloc.c 2005-03-10 14:42:43.000000000 -0800
+++ linux-2.6.11/mm/page_alloc.c 2005-03-10 15:01:53.000000000 -0800
@@ -628,11 +628,19 @@ void fastcall free_cold_page(struct page
free_hot_cold_page(page, 1);
}

-static inline void prep_zero_page(struct page *page, int order, int gfp_flags)
+void prep_zero_page(struct page *page, unsigned int order, unsigned int gfp_flags)
{
int i;

BUG_ON((gfp_flags & (__GFP_WAIT | __GFP_HIGHMEM)) == __GFP_HIGHMEM);
+
+#ifdef CONFIG_CLEAR_PAGES
+ if (!PageHighMem(page)) {
+ clear_pages(page_address(page), order);
+ return;
+ }
+#endif
+
for(i = 0; i < (1 << order); i++)
clear_highpage(page + i);
}
Index: linux-2.6.11/mm/hugetlb.c
===================================================================
--- linux-2.6.11.orig/mm/hugetlb.c 2005-03-01 23:38:12.000000000 -0800
+++ linux-2.6.11/mm/hugetlb.c 2005-03-10 15:01:53.000000000 -0800
@@ -78,7 +78,6 @@ void free_huge_page(struct page *page)
struct page *alloc_huge_page(void)
{
struct page *page;
- int i;

spin_lock(&hugetlb_lock);
page = dequeue_huge_page();
@@ -89,8 +88,7 @@ struct page *alloc_huge_page(void)
spin_unlock(&hugetlb_lock);
set_page_count(page, 1);
page[1].mapping = (void *)free_huge_page;
- for (i = 0; i < (HPAGE_SIZE/PAGE_SIZE); ++i)
- clear_highpage(&page[i]);
+ prep_zero_page(page, HUGETLB_PAGE_ORDER, GFP_HIGHUSER);
return page;
}

Index: linux-2.6.11/include/asm-ia64/page.h
===================================================================
--- linux-2.6.11.orig/include/asm-ia64/page.h 2005-03-01 23:37:48.000000000 -0800
+++ linux-2.6.11/include/asm-ia64/page.h 2005-03-10 15:02:47.000000000 -0800
@@ -56,8 +56,9 @@
# ifdef __KERNEL__
# define STRICT_MM_TYPECHECKS

-extern void clear_page (void *page);
+extern void clear_pages (void *page, int order);
extern void copy_page (void *to, void *from);
+#define clear_page(__page) clear_pages(__page, 0)

/*
* clear_user_page() and copy_user_page() can't be inline functions because
Index: linux-2.6.11/arch/ia64/kernel/ia64_ksyms.c
===================================================================
--- linux-2.6.11.orig/arch/ia64/kernel/ia64_ksyms.c 2005-03-01 23:38:08.000000000 -0800
+++ linux-2.6.11/arch/ia64/kernel/ia64_ksyms.c 2005-03-10 15:01:53.000000000 -0800
@@ -38,7 +38,7 @@ EXPORT_SYMBOL(__down_trylock);
EXPORT_SYMBOL(__up);

#include <asm/page.h>
-EXPORT_SYMBOL(clear_page);
+EXPORT_SYMBOL(clear_pages);

#ifdef CONFIG_VIRTUAL_MEM_MAP
#include <linux/bootmem.h>
Index: linux-2.6.11/arch/ia64/lib/clear_page.S
===================================================================
--- linux-2.6.11.orig/arch/ia64/lib/clear_page.S 2005-03-01 23:37:47.000000000 -0800
+++ linux-2.6.11/arch/ia64/lib/clear_page.S 2005-03-10 15:01:53.000000000 -0800
@@ -7,6 +7,7 @@
* 1/06/01 davidm Tuned for Itanium.
* 2/12/02 kchen Tuned for both Itanium and McKinley
* 3/08/02 davidm Some more tweaking
+ * 12/10/04 clameter Make it work on pages of order size
*/
#include <linux/config.h>

@@ -29,27 +30,33 @@
#define dst4 r11

#define dst_last r31
+#define totsize r14

-GLOBAL_ENTRY(clear_page)
+GLOBAL_ENTRY(clear_pages)
.prologue
- .regstk 1,0,0,0
- mov r16 = PAGE_SIZE/L3_LINE_SIZE-1 // main loop count, -1=repeat/until
+ .regstk 2,0,0,0
+ mov r16 = PAGE_SIZE/L3_LINE_SIZE // main loop count
+ mov totsize = PAGE_SIZE
.save ar.lc, saved_lc
mov saved_lc = ar.lc
-
+ ;;
.body
+ adds dst1 = 16, in0
mov ar.lc = (PREFETCH_LINES - 1)
mov dst_fetch = in0
- adds dst1 = 16, in0
adds dst2 = 32, in0
+ shl r16 = r16, in1
+ shl totsize = totsize, in1
;;
.fetch: stf.spill.nta [dst_fetch] = f0, L3_LINE_SIZE
adds dst3 = 48, in0 // executing this multiple times is harmless
br.cloop.sptk.few .fetch
+ add r16 = -1,r16
+ add dst_last = totsize, dst_fetch
+ adds dst4 = 64, in0
;;
- addl dst_last = (PAGE_SIZE - PREFETCH_LINES*L3_LINE_SIZE), dst_fetch
mov ar.lc = r16 // one L3 line per iteration
- adds dst4 = 64, in0
+ adds dst_last = -PREFETCH_LINES*L3_LINE_SIZE, dst_last
;;
#ifdef CONFIG_ITANIUM
// Optimized for Itanium
@@ -74,4 +81,4 @@ GLOBAL_ENTRY(clear_page)
;;
mov ar.lc = saved_lc // restore lc
br.ret.sptk.many rp
-END(clear_page)
+END(clear_pages)
Index: linux-2.6.11/include/asm-i386/page.h
===================================================================
--- linux-2.6.11.orig/include/asm-i386/page.h 2005-03-01 23:37:49.000000000 -0800
+++ linux-2.6.11/include/asm-i386/page.h 2005-03-10 15:02:59.000000000 -0800
@@ -18,7 +18,7 @@

#include <asm/mmx.h>

-#define clear_page(page) mmx_clear_page((void *)(page))
+#define clear_pages(page, order) mmx_clear_page((void *)(page),order)
#define copy_page(to,from) mmx_copy_page(to,from)

#else
@@ -28,11 +28,12 @@
* Maybe the K6-III ?
*/

-#define clear_page(page) memset((void *)(page), 0, PAGE_SIZE)
+#define clear_pages(page, order) memset((void *)(page), 0, PAGE_SIZE << (order))
#define copy_page(to,from) memcpy((void *)(to), (void *)(from), PAGE_SIZE)

#endif

+#define clear_page(page) clear_pages(page, 0)
#define clear_user_page(page, vaddr, pg) clear_page(page)
#define copy_user_page(to, from, vaddr, pg) copy_page(to, from)

Index: linux-2.6.11/include/asm-i386/mmx.h
===================================================================
--- linux-2.6.11.orig/include/asm-i386/mmx.h 2005-03-01 23:38:09.000000000 -0800
+++ linux-2.6.11/include/asm-i386/mmx.h 2005-03-10 15:01:53.000000000 -0800
@@ -8,7 +8,7 @@
#include <linux/types.h>

extern void *_mmx_memcpy(void *to, const void *from, size_t size);
-extern void mmx_clear_page(void *page);
+extern void mmx_clear_page(void *page, int order);
extern void mmx_copy_page(void *to, void *from);

#endif
Index: linux-2.6.11/arch/i386/lib/mmx.c
===================================================================
--- linux-2.6.11.orig/arch/i386/lib/mmx.c 2005-03-01 23:38:09.000000000 -0800
+++ linux-2.6.11/arch/i386/lib/mmx.c 2005-03-10 15:01:53.000000000 -0800
@@ -128,7 +128,7 @@ void *_mmx_memcpy(void *to, const void *
* other MMX using processors do not.
*/

-static void fast_clear_page(void *page)
+static void fast_clear_page(void *page, int order)
{
int i;

@@ -138,7 +138,7 @@ static void fast_clear_page(void *page)
" pxor %%mm0, %%mm0\n" : :
);

- for(i=0;i<4096/64;i++)
+ for(i=0;i<((4096/64) << order);i++)
{
__asm__ __volatile__ (
" movntq %%mm0, (%0)\n"
@@ -257,7 +257,7 @@ static void fast_copy_page(void *to, voi
* Generic MMX implementation without K7 specific streaming
*/

-static void fast_clear_page(void *page)
+static void fast_clear_page(void *page, int order)
{
int i;

@@ -267,7 +267,7 @@ static void fast_clear_page(void *page)
" pxor %%mm0, %%mm0\n" : :
);

- for(i=0;i<4096/128;i++)
+ for(i=0;i<((4096/128) << order);i++)
{
__asm__ __volatile__ (
" movq %%mm0, (%0)\n"
@@ -359,23 +359,23 @@ static void fast_copy_page(void *to, voi
* Favour MMX for page clear and copy.
*/

-static void slow_zero_page(void * page)
+static void slow_clear_page(void * page, int order)
{
int d0, d1;
__asm__ __volatile__( \
"cld\n\t" \
"rep ; stosl" \
: "=&c" (d0), "=&D" (d1)
- :"a" (0),"1" (page),"0" (1024)
+ :"a" (0),"1" (page),"0" (1024 << order)
:"memory");
}
-
-void mmx_clear_page(void * page)
+
+void mmx_clear_page(void * page, int order)
{
if(unlikely(in_interrupt()))
- slow_zero_page(page);
+ slow_clear_page(page, order);
else
- fast_clear_page(page);
+ fast_clear_page(page, order);
}

static void slow_copy_page(void *to, void *from)
Index: linux-2.6.11/include/asm-x86_64/page.h
===================================================================
--- linux-2.6.11.orig/include/asm-x86_64/page.h 2005-03-01 23:37:47.000000000 -0800
+++ linux-2.6.11/include/asm-x86_64/page.h 2005-03-10 15:03:10.000000000 -0800
@@ -32,8 +32,9 @@
#ifdef __KERNEL__
#ifndef __ASSEMBLY__

-void clear_page(void *);
+void clear_pages(void *, int);
void copy_page(void *, void *);
+#define clear_page(__page) clear_pages(__page, 0)

#define clear_user_page(page, vaddr, pg) clear_page(page)
#define copy_user_page(to, from, vaddr, pg) copy_page(to, from)
Index: linux-2.6.11/arch/x86_64/kernel/x8664_ksyms.c
===================================================================
--- linux-2.6.11.orig/arch/x86_64/kernel/x8664_ksyms.c 2005-03-01 23:37:49.000000000 -0800
+++ linux-2.6.11/arch/x86_64/kernel/x8664_ksyms.c 2005-03-10 15:01:53.000000000 -0800
@@ -108,7 +108,7 @@ EXPORT_SYMBOL(pci_mem_start);
#endif

EXPORT_SYMBOL(copy_page);
-EXPORT_SYMBOL(clear_page);
+EXPORT_SYMBOL(clear_pages);

EXPORT_SYMBOL(cpu_pda);
#ifdef CONFIG_SMP
Index: linux-2.6.11/arch/x86_64/lib/clear_page.S
===================================================================
--- linux-2.6.11.orig/arch/x86_64/lib/clear_page.S 2005-03-01 23:38:08.000000000 -0800
+++ linux-2.6.11/arch/x86_64/lib/clear_page.S 2005-03-10 15:01:53.000000000 -0800
@@ -1,12 +1,16 @@
/*
* Zero a page.
* rdi page
+ * rsi order
*/
- .globl clear_page
+ .globl clear_pages
.p2align 4
-clear_page:
+clear_pages:
+ movl $4096/64,%eax
+ movl %esi, %ecx
+ shll %cl, %eax
+ movl %eax, %ecx
xorl %eax,%eax
- movl $4096/64,%ecx
.p2align 4
.Lloop:
decl %ecx
@@ -23,7 +27,7 @@ clear_page:
jnz .Lloop
nop
ret
-clear_page_end:
+clear_pages_end:

/* C stepping K8 run faster using the string instructions.
It is also a lot simpler. Use this when possible */
@@ -32,19 +36,22 @@ clear_page_end:

.section .altinstructions,"a"
.align 8
- .quad clear_page
- .quad clear_page_c
+ .quad clear_pages
+ .quad clear_pages_c
.byte X86_FEATURE_K8_C
- .byte clear_page_end-clear_page
- .byte clear_page_c_end-clear_page_c
+ .byte clear_pages_end-clear_pages
+ .byte clear_pages_c_end-clear_pages_c
.previous

.section .altinstr_replacement,"ax"
-clear_page_c:
- movl $4096/8,%ecx
+clear_pages_c:
+ movl $4096/8,%eax
+ movl %esi, %ecx
+ shll %cl, %eax
+ movl %eax, %ecx
xorl %eax,%eax
rep
stosq
ret
-clear_page_c_end:
+clear_pages_c_end:
.previous
Index: linux-2.6.11/arch/sparc64/lib/clear_page.S
===================================================================
--- linux-2.6.11.orig/arch/sparc64/lib/clear_page.S 2005-03-01 23:38:17.000000000 -0800
+++ linux-2.6.11/arch/sparc64/lib/clear_page.S 2005-03-10 15:01:53.000000000 -0800
@@ -28,9 +28,12 @@
.text

.globl _clear_page
-_clear_page: /* %o0=dest */
+_clear_page: /* %o0=dest, %o1=order */
+ sethi %hi(PAGE_SIZE/64), %o2
+ clr %o4
+ or %o2, %lo(PAGE_SIZE/64), %o2
ba,pt %xcc, clear_page_common
- clr %o4
+ sllx %o2, %o1, %o1

/* This thing is pretty important, it shows up
* on the profiles via do_anonymous_page().
@@ -69,16 +72,16 @@ clear_user_page: /* %o0=dest, %o1=vaddr
flush %g6
wrpr %o4, 0x0, %pstate

+ sethi %hi(PAGE_SIZE/64), %o1
mov 1, %o4
+ or %o1, %lo(PAGE_SIZE/64), %o1

clear_page_common:
VISEntryHalf
membar #StoreLoad | #StoreStore | #LoadStore
fzero %f0
- sethi %hi(PAGE_SIZE/64), %o1
mov %o0, %g1 ! remember vaddr for tlbflush
fzero %f2
- or %o1, %lo(PAGE_SIZE/64), %o1
faddd %f0, %f2, %f4
fmuld %f0, %f2, %f6
faddd %f0, %f2, %f8
Index: linux-2.6.11/include/asm-sparc64/page.h
===================================================================
--- linux-2.6.11.orig/include/asm-sparc64/page.h 2005-03-01 23:38:07.000000000 -0800
+++ linux-2.6.11/include/asm-sparc64/page.h 2005-03-10 15:03:43.000000000 -0800
@@ -14,8 +14,10 @@

#ifndef __ASSEMBLY__

-extern void _clear_page(void *page);
-#define clear_page(X) _clear_page((void *)(X))
+extern void _clear_page(void *page, int order);
+#define clear_page(X) _clear_page((void *)(X), 0)
+#define clear_pages _clear_page
+
struct page;
extern void clear_user_page(void *addr, unsigned long vaddr, struct page *page);
#define copy_page(X,Y) memcpy((void *)(X), (void *)(Y), PAGE_SIZE)
Index: linux-2.6.11/include/linux/gfp.h
===================================================================
--- linux-2.6.11.orig/include/linux/gfp.h 2005-03-01 23:37:50.000000000 -0800
+++ linux-2.6.11/include/linux/gfp.h 2005-03-10 15:01:53.000000000 -0800
@@ -131,4 +131,5 @@ extern void FASTCALL(free_cold_page(stru

void page_alloc_init(void);

+void prep_zero_page(struct page *, unsigned int order, unsigned int gfp_flags);
#endif /* __LINUX_GFP_H */
Index: linux-2.6.11/arch/x86_64/Kconfig
===================================================================
--- linux-2.6.11.orig/arch/x86_64/Kconfig 2005-03-10 14:42:41.000000000 -0800
+++ linux-2.6.11/arch/x86_64/Kconfig 2005-03-10 15:01:53.000000000 -0800
@@ -78,6 +78,10 @@ config GENERIC_IOMAP
bool
default y

+config CLEAR_PAGES
+ bool
+ default y
+
source "init/Kconfig"


Index: linux-2.6.11/arch/i386/Kconfig
===================================================================
--- linux-2.6.11.orig/arch/i386/Kconfig 2005-03-10 14:42:41.000000000 -0800
+++ linux-2.6.11/arch/i386/Kconfig 2005-03-10 15:01:53.000000000 -0800
@@ -33,6 +33,10 @@ config GENERIC_IOMAP
bool
default y

+config CLEAR_PAGES
+ bool
+ default y
+
source "init/Kconfig"

menu "Processor type and features"
Index: linux-2.6.11/arch/ia64/Kconfig
===================================================================
--- linux-2.6.11.orig/arch/ia64/Kconfig 2005-03-01 23:38:26.000000000 -0800
+++ linux-2.6.11/arch/ia64/Kconfig 2005-03-10 15:01:53.000000000 -0800
@@ -46,6 +46,10 @@ config GENERIC_IOMAP
bool
default y

+config CLEAR_PAGES
+ bool
+ default y
+
choice
prompt "System type"
default IA64_GENERIC
Index: linux-2.6.11/arch/sparc64/Kconfig
===================================================================
--- linux-2.6.11.orig/arch/sparc64/Kconfig 2005-03-01 23:38:25.000000000 -0800
+++ linux-2.6.11/arch/sparc64/Kconfig 2005-03-10 15:02:16.000000000 -0800
@@ -16,6 +16,10 @@ config TIME_INTERPOLATION
bool
default y

+config CLEAR_PAGES
+ bool
+ default y
+
source "init/Kconfig"

config SYSVIPC_COMPAT
-
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