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| author | Kirill A. Shutemov <kirill@shutemov.name> | 2009-09-15 11:26:33 +0200 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2009-09-15 23:07:02 +0200 |
| commit | dca230f00d737353e2dffae489c916b41971921f (patch) | |
| tree | 49490aab441deb87d7f9df5f0d737dad51d454fb /arch/arm | |
| parent | ARM: 5700/1: ARM: Introduce ARM_L1_CACHE_SHIFT to define cache line size (diff) | |
| download | linux-dca230f00d737353e2dffae489c916b41971921f.tar.xz linux-dca230f00d737353e2dffae489c916b41971921f.zip | |
ARM: 5701/1: ARM: copy_page.S: take into account the size of the cache line
Optimized version of copy_page() was written with assumption that cache
line size is 32 bytes. On Cortex-A8 cache line size is 64 bytes.
This patch tries to generalize copy_page() to work with any cache line
size if cache line size is multiple of 16 and page size is multiple of
two cache line size.
After this optimization we've got ~25% speedup on OMAP3(tested in
userspace).
There is test for kernelspace which trigger copy-on-write after fork():
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#define BUF_SIZE (10000*4096)
#define NFORK 200
int main(int argc, char **argv)
{
char *buf = malloc(BUF_SIZE);
int i;
memset(buf, 0, BUF_SIZE);
for(i = 0; i < NFORK; i++) {
if (fork()) {
wait(NULL);
} else {
int j;
for(j = 0; j < BUF_SIZE; j+= 4096)
buf[j] = (j & 0xFF) + 1;
break;
}
}
free(buf);
return 0;
}
Before optimization this test takes ~66 seconds, after optimization
takes ~56 seconds.
Signed-off-by: Siarhei Siamashka <siarhei.siamashka@nokia.com>
Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm')
| -rw-r--r-- | arch/arm/lib/copy_page.S | 16 |
1 files changed, 8 insertions, 8 deletions
diff --git a/arch/arm/lib/copy_page.S b/arch/arm/lib/copy_page.S index 6ae04db1ca4f..6ee2f6706f86 100644 --- a/arch/arm/lib/copy_page.S +++ b/arch/arm/lib/copy_page.S @@ -12,8 +12,9 @@ #include <linux/linkage.h> #include <asm/assembler.h> #include <asm/asm-offsets.h> +#include <asm/cache.h> -#define COPY_COUNT (PAGE_SZ/64 PLD( -1 )) +#define COPY_COUNT (PAGE_SZ / (2 * L1_CACHE_BYTES) PLD( -1 )) .text .align 5 @@ -26,17 +27,16 @@ ENTRY(copy_page) stmfd sp!, {r4, lr} @ 2 PLD( pld [r1, #0] ) - PLD( pld [r1, #32] ) + PLD( pld [r1, #L1_CACHE_BYTES] ) mov r2, #COPY_COUNT @ 1 ldmia r1!, {r3, r4, ip, lr} @ 4+1 -1: PLD( pld [r1, #64] ) - PLD( pld [r1, #96] ) -2: stmia r0!, {r3, r4, ip, lr} @ 4 - ldmia r1!, {r3, r4, ip, lr} @ 4+1 - stmia r0!, {r3, r4, ip, lr} @ 4 - ldmia r1!, {r3, r4, ip, lr} @ 4+1 +1: PLD( pld [r1, #2 * L1_CACHE_BYTES]) + PLD( pld [r1, #3 * L1_CACHE_BYTES]) +2: + .rept (2 * L1_CACHE_BYTES / 16 - 1) stmia r0!, {r3, r4, ip, lr} @ 4 ldmia r1!, {r3, r4, ip, lr} @ 4 + .endr subs r2, r2, #1 @ 1 stmia r0!, {r3, r4, ip, lr} @ 4 ldmgtia r1!, {r3, r4, ip, lr} @ 4 |