>> That's true, but I think the most important case is lcd scrolling,
>> where it's usually a big power of two -- that's where we had the #ifdef,
>> so the problem was known, I suppose.
>
> I think the most important case for *you* is lcd scrolling, but for 99%
> of everyone else, it isn't at all:)
Well, its a big memcpy, and it has direct effect on the user. Every
other copy is smaller, or has no interactive value.
> memcpy() and memset() are used 100 times more often in non-lcd
> related code and most boards don't even have LCDs.
That's true. But it's only a boot loader (I just looked at what Nicolas
Pitre did in the kernel for ARM strcpy and, well....).
So I made some measures (it's one of Pike's rules of programming:
* Rule 2. Measure. Don't tune for speed until you've measured, and even
then don't unless one part of the code overwhelms the rest.
)
I booted in u-boot, typed "setenv stdout serial" then "boot", which goes
over the ethernet. Stopped the system after u-boot gave over control to
the kernel. Result: 10412 memcopies so divided (number, length):
3941 4
1583 6
772 20
1 46
1 47
3 60
1024 64
1 815
1 888
770 1148
1543 1480
1 2283
1 3836
770 4096
So I dare say non-power-of-4 is a minority anyways: 1587 calls, 12689 bytes.
i.e. 15.2% of the calls and 0.2% of the data.
Data collected in memory with patch below, used with following line:
od -An -t d4 logfile | awk '{print $4}' | sort -n | uniq -c
diff --git a/include/configs/nhk8815.h b/include/configs/nhk8815.h
index edd698e..a390f28 100644
--- a/include/configs/nhk8815.h
+++ b/include/configs/nhk8815.h
@@ -28,6 +28,8 @@
#include <nomadik.h>
+#define CONFIG_MCLOGSIZE (16*1024)
+
#define CONFIG_ARM926EJS
#define CONFIG_NOMADIK
#define CONFIG_NOMADIK_8815 /* cpu variant */
diff --git a/lib_generic/string.c b/lib_generic/string.c
index 5f7aff9..5afa11e 100644
--- a/lib_generic/string.c
+++ b/lib_generic/string.c
@@ -19,6 +19,7 @@
#include <linux/string.h>
#include <linux/ctype.h>
#include <malloc.h>
+#include <common.h>
#if 0 /* not used - was: #ifndef __HAVE_ARCH_STRNICMP */
@@ -461,11 +462,29 @@ char * bcopy(const char * src, char * dest, int count)
* You should not use this function to access IO space, use memcpy_toio()
* or memcpy_fromio() instead.
*/
+
+#ifndef CONFIG_MCLOGSIZE /* if you want to log the memcpy calls, define it */
+#define CONFIG_MCLOGSIZE 0
+#endif
+struct mclog {int idx; void *dst; const void *src; int cnt;};
+static struct mclog mclog[CONFIG_MCLOGSIZE];
+
void * memcpy(void *dest, const void *src, size_t count)
{
char *d8 = (char *)dest, *s8 = (char *)src;
unsigned long *dl = (unsigned long *)dest, *sl = (unsigned long *)src;
+ if (CONFIG_MCLOGSIZE) {
+ static int idx;
+ struct mclog *p = mclog + (idx % (CONFIG_MCLOGSIZE ?: 1));
+ if (!idx) printf("memcpy log at %p, size 0x%x\n",
+ mclog, sizeof(mclog));
+ p->idx = idx++;
+ p->dst = dest;
+ p->src = src;
+ p->cnt = count;
+ }
+
/* if all data is aligned (common case), copy a word at a time */
if ( (((int)dest | (int)src | count) & (sizeof(long) - 1)) == 0) {
count /= sizeof(unsigned long);
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