This patch is a reorganization and optimization of the get_order()
function. It also fixes some obvious, blatant and stupid errors I
did in the first release; the speed up is also higher.
Currently each architecture defines its version in
asm-${ARCH}/page.h, being most of them the same function. I have
unified the implementation in asm-generic/page.h, as
generic_get_order(). Then each arch can implement it's own version
or use the generic one [as the patch stands now, every
architecture that had the generic version uses
generic_get_oder()].
The optimization is done in the way the generic_get_order() is
implemented; currently it is a loop - however, that can be highly
optimized by using fls() [available on each architecture or as
generic_tls() where not optimized].
On my tests in a tight loop doing repeated get_order() calls (see
included test program), I got an aprox average run time of 6m24s
for the unoptimized version (the old one, executing "time ./goo -v
speed-new") and 2m32s for the optimized version (executing "time
./goo -v speed-old"). The test machine is a 2xP3 933MHhz 1.5GB.
Even using generic_fls() on ia32 yields better results - my guess
is it caused for it being a fixed-path functio instead of a for
loop.
I was only able to test it and try it in ia32, so I don't know if
I broke anything else in other archs; reports welcome.
CAVEATS:
- the #include <asm-generic/page.h> ... I don't know if it is the
best way to do it. Any ideas?
- Some arches still define fls() as the generic_fls(), instead of
using bit-searching ASM instructions - I lack the knowledge to
fix it, though.
Test program (patch follows):
compile with 'cc -Iinclude/ -Wall -g -O2 goo.c -o goo' from the
root of the patched linux kernel tree.
#define __KERNEL__
#define __ASSEMBLY__
#include "asm-i386/bitops.h"
#include "asm-i386/page.h"
#include "asm-generic/page.h"
#include <stdio.h>
#include <getopt.h>
#include <stdlib.h>
/* Old, unoptimized version */
static __inline__
int get_order_0 (unsigned long size)
{
int order;
size = (size-1) >> (PAGE_SHIFT-1);
order = -1;
do {
size >>= 1;
order++;
} while (size);
return order;
}
unsigned long verbose_step = 0;
static __inline__
void progress (unsigned long cnt)
{
if (verbose_step && (cnt % verbose_step) == 0)
printf ("Going through %lu\n", cnt);
}
void help (FILE *f)
{
fprintf (f,
"Usage: goo [-b BOTTOM] [-t TOP] [-s STEP] [-v VSTEP] [-h]\n"
" {verify,speed-new,speed-old}\n"
"\n"
"-b BOTTOM where to start counting [0]\n"
"-t TOP where to stop counting [~0UL]\n"
"-s STEP count increment [1]\n"
"-v VSTEP Every VSTEP report the count [0]\n"
"\n"
"verify Verify that the old and new implementations behave the same\n"
" from BOTTOM to TOP with STEP.\n"
"\n"
"speed-new Call the optimized get_order() for all the numbers from\n"
" BOTTOM to TOP with STEP.\n"
"\n"
"speed-old Call the original get_order() for all the numbers from\n"
" BOTTOM to TOP with STEP.\n"
"\n"
"It is nice to have a wide range, so that the timing is better; use -v\n"
"if you want reporting because it feels nice. The default range covers\n"
"all that an unsigned long can hold.\n"
);
}
/* Test driver
**
** We just count from 0 to ~0UL; in verify mode, we verify that
** _every_ number get's the same order with the old and new
** versions. In the speed mode we just run in a tight loop so that
** it can be rawly measured how fast is the new version (speed-new)
** against the old version (speed-old). time(1) is your friend.
*/
int main (int argc, char **argv)
{
const char *mode;
int opterr, c;
unsigned long bottom = 0,
top = ~0UL,
step = 1,
dummy = 0,
cnt;
opterr = 0;
while ((c = getopt (argc, argv, "b:t:s:v:h")) != -1)
switch (c) {
case 'b':
bottom = strtoul (optarg, NULL, 10);
break;
case 't':
top = strtoul (optarg, NULL, 10);
break;
case 's':
step = strtoul (optarg, NULL, 10);
break;
case 'v':
verbose_step = strtoul (optarg, NULL, 10);
break;
case 'h':
help (stdout);
exit (0);
break;
case '?':
default:
fprintf (stderr, "Unknown option %s\n", argv[optind]);
help (stderr);
exit (1);
}
if (argc < 2) {
help (stderr);
return 1;
}
mode = argv[optind];
if (!strcmp (mode, "verify")) {
for (cnt = bottom; cnt < top; cnt += step) {
if (get_order_0 (cnt) != generic_get_order (cnt))
printf ("error: %lu - different results\n", cnt);
progress (cnt);
}
}
else if (!strcmp (mode, "speed-old")) {
for (cnt = bottom; cnt < top; cnt += step) {
dummy += get_order_0 (cnt);
progress (cnt);
}
}
else if (!strcmp (mode, "speed-new")) {
for (cnt = bottom; cnt < top; cnt += step) {
dummy += generic_get_order (cnt);
progress (cnt);
}
}
else {
fprintf (stderr, "Unknown mode\n");
help (stderr);
exit (1);
}
printf ("accumulated dummy = %lu\n", dummy);
return 0;
}
/*
** Local Variables:
** compile-command: "cc -Iinclude/ -Wall -g -O2 goo.c -o goo"
** End:
*/
This patch is against 2.5.47.
diff -u include/asm-alpha/page.h:1.1.1.1 include/asm-alpha/page.h:1.1.1.1.16.1
--- include/asm-alpha/page.h:1.1.1.1 Tue Oct 8 19:47:09 2002
+++ include/asm-alpha/page.h Tue Nov 12 16:49:22 2002
@@ -67,18 +67,17 @@
#define PAGE_BUG(page) BUG()
-/* Pure 2^n version of get_order */
-extern __inline__ int get_order(unsigned long size)
-{
- int order;
- size = (size-1) >> (PAGE_SHIFT-1);
- order = -1;
- do {
- size >>= 1;
- order++;
- } while (size);
- return order;
+/* Return 'n' in how many 2^n pages are needed to store s bytes.
+** (n == 0 for s == 0)
+*/
+
+#include <asm-generic/page.h>
+
+static __inline__
+int get_order (unsigned long s)
+{
+ return generic_get_order (s);
}
#endif /* !__ASSEMBLY__ */
diff -u include/asm-arm/page.h:1.1.1.2 include/asm-arm/page.h:1.1.1.2.10.1
--- include/asm-arm/page.h:1.1.1.2 Thu Oct 17 13:08:30 2002
+++ include/asm-arm/page.h Tue Nov 12 16:49:22 2002
@@ -175,18 +175,16 @@
#endif
-/* Pure 2^n version of get_order */
-static inline int get_order(unsigned long size)
-{
- int order;
+/* Return 'n' in how many 2^n pages are needed to store s bytes.
+** (n == 0 for s == 0)
+*/
+
+#include <asm-generic/page.h>
- size = (size-1) >> (PAGE_SHIFT-1);
- order = -1;
- do {
- size >>= 1;
- order++;
- } while (size);
- return order;
+static __inline__
+int get_order (unsigned long s)
+{
+ return generic_get_order (s);
}
#include <asm/memory.h>
diff -u /dev/null include/asm-generic/page.h:1.1.2.2
--- /dev/null Wed Nov 13 17:05:37 2002
+++ include/asm-generic/page.h Wed Nov 13 14:58:51 2002
@@ -0,0 +1,20 @@
+#ifndef _GENERIC_PAGE_H
+#define _GENERIC_PAGE_H
+
+#include <asm/bitops.h>
+
+/* Return 'n' in how many 2^n pages are needed to store s bytes.
+** (n == 0 for s == 0)
+*/
+
+static __inline__
+int generic_get_order (unsigned long s)
+{
+ s = (s - 1) >> PAGE_SHIFT;
+ if (s == 0)
+ return 0;
+ return fls (s);
+}
+
+#endif _GENERIC_PAGE_H
+
diff -u include/asm-i386/bitops.h:1.1.1.2 include/asm-i386/bitops.h:1.1.1.2.4.1
--- include/asm-i386/bitops.h:1.1.1.2 Mon Nov 11 20:02:12 2002
+++ include/asm-i386/bitops.h Tue Nov 12 16:49:22 2002
@@ -414,11 +414,19 @@
return word;
}
-/*
- * fls: find last bit set.
+/**
+ * __fls - find last bit in word.
+ * @word: The word to search
+ *
+ * Undefined if no bit exists, so code should check against 0 first.
*/
-
-#define fls(x) generic_fls(x)
+static __inline__ unsigned long __fls(unsigned long word)
+{
+ __asm__("bsrl %1,%0"
+ :"=r" (word)
+ :"rm" (word));
+ return word;
+}
#ifdef __KERNEL__
@@ -454,6 +462,23 @@
int r;
__asm__("bsfl %1,%0\n\t"
+ "jnz 1f\n\t"
+ "movl $-1,%0\n"
+ "1:" : "=r" (r) : "g" (x));
+ return r+1;
+}
+
+/**
+ * fls - find last bit set
+ * @x: the word to search
+ *
+ * Check out comments for ffs()
+ */
+static __inline__ int fls(int x)
+{
+ int r;
+
+ __asm__("bsrl %1,%0\n\t"
"jnz 1f\n\t"
"movl $-1,%0\n"
"1:" : "=r" (r) : "g" (x));
diff -u include/asm-i386/page.h:1.1.1.2 include/asm-i386/page.h:1.1.1.2.10.1
--- include/asm-i386/page.h:1.1.1.2 Thu Oct 17 13:06:36 2002
+++ include/asm-i386/page.h Tue Nov 12 16:49:22 2002
@@ -120,18 +120,17 @@
BUG(); \
} while (0)
-/* Pure 2^n version of get_order */
-static __inline__ int get_order(unsigned long size)
-{
- int order;
- size = (size-1) >> (PAGE_SHIFT-1);
- order = -1;
- do {
- size >>= 1;
- order++;
- } while (size);
- return order;
+/* Return 'n' in how many 2^n pages are needed to store s bytes.
+** (n == 0 for s == 0)
+*/
+
+#include <asm-generic/page.h>
+
+static __inline__
+int get_order (unsigned long s)
+{
+ return generic_get_order (s);
}
#endif /* __ASSEMBLY__ */
diff -u include/asm-m68k/page.h:1.1.1.2 include/asm-m68k/page.h:1.1.1.2.4.1
--- include/asm-m68k/page.h:1.1.1.2 Mon Nov 4 18:10:53 2002
+++ include/asm-m68k/page.h Tue Nov 12 16:49:22 2002
@@ -100,18 +100,17 @@
/* to align the pointer to the (next) page boundary */
#define PAGE_ALIGN(addr) (((addr)+PAGE_SIZE-1)&PAGE_MASK)
-/* Pure 2^n version of get_order */
-extern __inline__ int get_order(unsigned long size)
-{
- int order;
- size = (size-1) >> (PAGE_SHIFT-1);
- order = -1;
- do {
- size >>= 1;
- order++;
- } while (size);
- return order;
+/* Return 'n' in how many 2^n pages are needed to store s bytes.
+** (n == 0 for s == 0)
+*/
+
+#include <asm-generic/page.h>
+
+static __inline__
+int get_order (unsigned long s)
+{
+ return generic_get_order (s);
}
#endif /* !__ASSEMBLY__ */
diff -u include/asm-m68knommu/page.h:1.1.2.1 include/asm-m68knommu/page.h:1.1.2.1.4.1
--- include/asm-m68knommu/page.h:1.1.2.1 Mon Nov 4 18:10:53 2002
+++ include/asm-m68knommu/page.h Tue Nov 12 16:49:22 2002
@@ -51,19 +51,18 @@
/* to align the pointer to the (next) page boundary */
#define PAGE_ALIGN(addr) (((addr)+PAGE_SIZE-1)&PAGE_MASK)
-/* Pure 2^n version of get_order */
-extern __inline__ int get_order(unsigned long size)
-{
- int order;
+/* Return 'n' in how many 2^n pages are needed to store s bytes.
+** (n == 0 for s == 0)
+*/
+
+#include <asm-generic/page.h>
- size = (size-1) >> (PAGE_SHIFT-1);
- order = -1;
- do {
- size >>= 1;
- order++;
- } while (size);
- return order;
+static __inline__
+int get_order (unsigned long s)
+{
+ return generic_get_order (s);
}
+
extern unsigned long memory_start;
extern unsigned long memory_end;
diff -u include/asm-mips/page.h:1.1.1.1 include/asm-mips/page.h:1.1.1.1.16.1
--- include/asm-mips/page.h:1.1.1.1 Tue Oct 8 19:47:08 2002
+++ include/asm-mips/page.h Tue Nov 12 16:49:22 2002
@@ -49,18 +49,16 @@
#define __pgd(x) ((pgd_t) { (x) } )
#define __pgprot(x) ((pgprot_t) { (x) } )
-/* Pure 2^n version of get_order */
-extern __inline__ int get_order(unsigned long size)
-{
- int order;
+/* Return 'n' in how many 2^n pages are needed to store s bytes.
+** (n == 0 for s == 0)
+*/
+
+#include <asm-generic/page.h>
- size = (size-1) >> (PAGE_SHIFT-1);
- order = -1;
- do {
- size >>= 1;
- order++;
- } while (size);
- return order;
+static __inline__
+int get_order (unsigned long s)
+{
+ return generic_get_order (s);
}
#endif /* _LANGUAGE_ASSEMBLY */
diff -u include/asm-parisc/page.h:1.1.1.2 include/asm-parisc/page.h:1.1.1.2.6.1
--- include/asm-parisc/page.h:1.1.1.2 Thu Oct 31 15:28:28 2002
+++ include/asm-parisc/page.h Tue Nov 12 16:49:22 2002
@@ -53,19 +53,18 @@
#define __pgd(x) ((pgd_t) { (x) } )
#define __pgprot(x) ((pgprot_t) { (x) } )
-/* Pure 2^n version of get_order */
-extern __inline__ int get_order(unsigned long size)
-{
- int order;
+/* Return 'n' in how many 2^n pages are needed to store s bytes.
+** (n == 0 for s == 0)
+*/
+
+#include <asm-generic/page.h>
- size = (size-1) >> (PAGE_SHIFT-1);
- order = -1;
- do {
- size >>= 1;
- order++;
- } while (size);
- return order;
+static __inline__
+int get_order (unsigned long s)
+{
+ return generic_get_order (s);
}
+
#ifdef __LP64__
#define MAX_PHYSMEM_RANGES 8 /* Fix the size for now (current known max is 3) */
diff -u include/asm-ppc64/page.h:1.1.1.1 include/asm-ppc64/page.h:1.1.1.1.16.1
--- include/asm-ppc64/page.h:1.1.1.1 Tue Oct 8 19:47:06 2002
+++ include/asm-ppc64/page.h Tue Nov 12 16:49:22 2002
@@ -119,19 +119,18 @@
#define PAGE_BUG(page) do { BUG(); } while (0)
-/* Pure 2^n version of get_order */
-static inline int get_order(unsigned long size)
-{
- int order;
+/* Return 'n' in how many 2^n pages are needed to store s bytes.
+** (n == 0 for s == 0)
+*/
+
+#include <asm-generic/page.h>
- size = (size-1) >> (PAGE_SHIFT-1);
- order = -1;
- do {
- size >>= 1;
- order++;
- } while (size);
- return order;
+static __inline__
+int get_order (unsigned long s)
+{
+ return generic_get_order (s);
}
+
#define __pa(x) ((unsigned long)(x)-PAGE_OFFSET)
diff -u include/asm-s390/page.h:1.1.1.1 include/asm-s390/page.h:1.1.1.1.16.1
--- include/asm-s390/page.h:1.1.1.1 Tue Oct 8 19:47:08 2002
+++ include/asm-s390/page.h Tue Nov 12 16:49:22 2002
@@ -71,18 +71,16 @@
BUG(); \
} while (0)
-/* Pure 2^n version of get_order */
-extern __inline__ int get_order(unsigned long size)
-{
- int order;
+/* Return 'n' in how many 2^n pages are needed to store s bytes.
+** (n == 0 for s == 0)
+*/
+
+#include <asm-generic/page.h>
- size = (size-1) >> (PAGE_SHIFT-1);
- order = -1;
- do {
- size >>= 1;
- order++;
- } while (size);
- return order;
+static __inline__
+int get_order (unsigned long s)
+{
+ return generic_get_order (s);
}
/*
diff -u include/asm-s390x/page.h:1.1.1.1 include/asm-s390x/page.h:1.1.1.1.16.1
--- include/asm-s390x/page.h:1.1.1.1 Tue Oct 8 19:47:05 2002
+++ include/asm-s390x/page.h Tue Nov 12 16:49:22 2002
@@ -69,18 +69,16 @@
BUG(); \
} while (0)
-/* Pure 2^n version of get_order */
-extern __inline__ int get_order(unsigned long size)
-{
- int order;
+/* Return 'n' in how many 2^n pages are needed to store s bytes.
+** (n == 0 for s == 0)
+*/
+
+#include <asm-generic/page.h>
- size = (size-1) >> (PAGE_SHIFT-1);
- order = -1;
- do {
- size >>= 1;
- order++;
- } while (size);
- return order;
+static __inline__
+int get_order (unsigned long s)
+{
+ return generic_get_order (s);
}
/*
diff -u include/asm-sh/page.h:1.1.1.1 include/asm-sh/page.h:1.1.1.1.16.1
--- include/asm-sh/page.h:1.1.1.1 Tue Oct 8 19:47:10 2002
+++ include/asm-sh/page.h Tue Nov 12 16:49:22 2002
@@ -102,19 +102,18 @@
BUG(); \
} while (0)
-/* Pure 2^n version of get_order */
-static __inline__ int get_order(unsigned long size)
-{
- int order;
+/* Return 'n' in how many 2^n pages are needed to store s bytes.
+** (n == 0 for s == 0)
+*/
+
+#include <asm-generic/page.h>
- size = (size-1) >> (PAGE_SHIFT-1);
- order = -1;
- do {
- size >>= 1;
- order++;
- } while (size);
- return order;
+static __inline__
+int get_order (unsigned long s)
+{
+ return generic_get_order (s);
}
+
#endif
diff -u include/asm-sparc/page.h:1.1.1.1 include/asm-sparc/page.h:1.1.1.1.16.1
--- include/asm-sparc/page.h:1.1.1.1 Tue Oct 8 19:47:09 2002
+++ include/asm-sparc/page.h Tue Nov 12 16:49:22 2002
@@ -147,19 +147,18 @@
#define TASK_UNMAPPED_BASE BTFIXUP_SETHI(sparc_unmapped_base)
-/* Pure 2^n version of get_order */
-extern __inline__ int get_order(unsigned long size)
-{
- int order;
+/* Return 'n' in how many 2^n pages are needed to store s bytes.
+** (n == 0 for s == 0)
+*/
+
+#include <asm-generic/page.h>
- size = (size-1) >> (PAGE_SHIFT-1);
- order = -1;
- do {
- size >>= 1;
- order++;
- } while (size);
- return order;
+static __inline__
+int get_order (unsigned long s)
+{
+ return generic_get_order (s);
}
+
#else /* !(__ASSEMBLY__) */
diff -u include/asm-sparc64/page.h:1.1.1.2 include/asm-sparc64/page.h:1.1.1.2.6.1
--- include/asm-sparc64/page.h:1.1.1.2 Thu Oct 31 15:28:29 2002
+++ include/asm-sparc64/page.h Tue Nov 12 16:49:22 2002
@@ -161,18 +161,16 @@
extern struct sparc_phys_banks sp_banks[SPARC_PHYS_BANKS];
-/* Pure 2^n version of get_order */
-static __inline__ int get_order(unsigned long size)
-{
- int order;
+/* Return 'n' in how many 2^n pages are needed to store s bytes.
+** (n == 0 for s == 0)
+*/
+
+#include <asm-generic/page.h>
- size = (size-1) >> (PAGE_SHIFT-1);
- order = -1;
- do {
- size >>= 1;
- order++;
- } while (size);
- return order;
+static __inline__
+int get_order (unsigned long s)
+{
+ return generic_get_order (s);
}
#endif /* !(__ASSEMBLY__) */
diff -u include/asm-v850/page.h:1.1.2.1 include/asm-v850/page.h:1.1.2.1.4.1
--- include/asm-v850/page.h:1.1.2.1 Mon Nov 4 18:10:54 2002
+++ include/asm-v850/page.h Tue Nov 12 16:49:22 2002
@@ -98,19 +98,18 @@
#define BUG() __bug()
#define PAGE_BUG(page) __bug()
-/* Pure 2^n version of get_order */
-extern __inline__ int get_order (unsigned long size)
-{
- int order;
+/* Return 'n' in how many 2^n pages are needed to store s bytes.
+** (n == 0 for s == 0)
+*/
+
+#include <asm-generic/page.h>
- size = (size-1) >> (PAGE_SHIFT-1);
- order = -1;
- do {
- size >>= 1;
- order++;
- } while (size);
- return order;
+static __inline__
+int get_order (unsigned long s)
+{
+ return generic_get_order (s);
}
+
#endif /* !__ASSEMBLY__ */
diff -u include/asm-x86_64/page.h:1.1.1.2 include/asm-x86_64/page.h:1.1.1.2.10.1
--- include/asm-x86_64/page.h:1.1.1.2 Thu Oct 17 13:08:31 2002
+++ include/asm-x86_64/page.h Tue Nov 12 16:49:22 2002
@@ -80,19 +80,18 @@
#define PAGE_BUG(page) BUG()
void out_of_line_bug(void);
-/* Pure 2^n version of get_order */
-extern __inline__ int get_order(unsigned long size)
-{
- int order;
+/* Return 'n' in how many 2^n pages are needed to store s bytes.
+** (n == 0 for s == 0)
+*/
+
+#include <asm-generic/page.h>
- size = (size-1) >> (PAGE_SHIFT-1);
- order = -1;
- do {
- size >>= 1;
- order++;
- } while (size);
- return order;
+static __inline__
+int get_order (unsigned long s)
+{
+ return generic_get_order (s);
}
+
#endif /* __ASSEMBLY__ */
--Inaky Perez-Gonzalez -- Not speaking for Intel - opinions are my own [or my fault] - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/