Re: page_add/remove_rmap costs

[Andrew Morton <akpm@zip.com.au>]

John Levon wrote:
> 
> On Wed, Jul 24, 2002 at 10:14:37PM -0700, Andrew Morton wrote:
> 
> > > c0135667 1095488  16.8865     .text.lock.page_alloc   /boot/vmlinux-2.5.28-3
> >
> > zone->lock?
> 
> I wrote a patch some time ago to remove all this guesswork on lock call
> sites :
> 

Me too, but I just killed all the out-of-line gunk, so the cost
is shown at the actual callsite.


--- 2.5.24/include/asm-i386/spinlock.h~spinlock-inline	Fri Jun 21 13:12:01 2002
+++ 2.5.24-akpm/include/asm-i386/spinlock.h	Fri Jun 21 13:18:12 2002
@@ -46,13 +46,13 @@ typedef struct {
 	"\n1:\t" \
 	"lock ; decb %0\n\t" \
 	"js 2f\n" \
-	LOCK_SECTION_START("") \
+	"jmp 3f\n" \
 	"2:\t" \
 	"cmpb $0,%0\n\t" \
 	"rep;nop\n\t" \
 	"jle 2b\n\t" \
 	"jmp 1b\n" \
-	LOCK_SECTION_END
+	"3:\t" \
 
 /*
  * This works. Despite all the confusion.
--- 2.5.24/include/asm-i386/rwlock.h~spinlock-inline	Fri Jun 21 13:18:33 2002
+++ 2.5.24-akpm/include/asm-i386/rwlock.h	Fri Jun 21 13:22:09 2002
@@ -22,25 +22,19 @@
 
 #define __build_read_lock_ptr(rw, helper)   \
 	asm volatile(LOCK "subl $1,(%0)\n\t" \
-		     "js 2f\n" \
-		     "1:\n" \
-		     LOCK_SECTION_START("") \
-		     "2:\tcall " helper "\n\t" \
-		     "jmp 1b\n" \
-		     LOCK_SECTION_END \
+		     "jns 1f\n\t" \
+		     "call " helper "\n\t" \
+		     "1:\t" \
 		     ::"a" (rw) : "memory")
 
 #define __build_read_lock_const(rw, helper)   \
 	asm volatile(LOCK "subl $1,%0\n\t" \
-		     "js 2f\n" \
-		     "1:\n" \
-		     LOCK_SECTION_START("") \
-		     "2:\tpushl %%eax\n\t" \
+		     "jns 1f\n\t" \
+		     "pushl %%eax\n\t" \
 		     "leal %0,%%eax\n\t" \
 		     "call " helper "\n\t" \
 		     "popl %%eax\n\t" \
-		     "jmp 1b\n" \
-		     LOCK_SECTION_END \
+		     "1:\t" \
 		     :"=m" (*(volatile int *)rw) : : "memory")
 
 #define __build_read_lock(rw, helper)	do { \
@@ -52,25 +46,19 @@
 
 #define __build_write_lock_ptr(rw, helper) \
 	asm volatile(LOCK "subl $" RW_LOCK_BIAS_STR ",(%0)\n\t" \
-		     "jnz 2f\n" \
+		     "jz 1f\n\t" \
+		     "call " helper "\n\t" \
 		     "1:\n" \
-		     LOCK_SECTION_START("") \
-		     "2:\tcall " helper "\n\t" \
-		     "jmp 1b\n" \
-		     LOCK_SECTION_END \
 		     ::"a" (rw) : "memory")
 
 #define __build_write_lock_const(rw, helper) \
 	asm volatile(LOCK "subl $" RW_LOCK_BIAS_STR ",%0\n\t" \
-		     "jnz 2f\n" \
-		     "1:\n" \
-		     LOCK_SECTION_START("") \
-		     "2:\tpushl %%eax\n\t" \
+		     "jz 1f\n\t" \
+		     "pushl %%eax\n\t" \
 		     "leal %0,%%eax\n\t" \
 		     "call " helper "\n\t" \
 		     "popl %%eax\n\t" \
-		     "jmp 1b\n" \
-		     LOCK_SECTION_END \
+		     "1:\n" \
 		     :"=m" (*(volatile int *)rw) : : "memory")
 
 #define __build_write_lock(rw, helper)	do { \

-
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