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mm/sparse: remove duplicated pfn_to_section_nr()

PATCH RESEND In review [email protected] 3 participants 3 messages Mar 16, 2020 – Mar 21, 2020

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Memory management MM core MGLRU
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#0 lore raw

PATCH RESEND 1/1 mm/sparse: remove duplicated pfn_to_section_nr()

From: chenqiwu <[email protected]>

Remove duplicated pfn_to_section_nr() in pfn_valid() and pfn_present() to increase executing efficiency of code.

Signed-off-by chenqiwu <[email protected]>
---
 include/linux/mmzone.h | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)
include/linux/mmzone.h +7 -4
index 462f687..35763b5 100644
@@ -1358,10 +1358,11 @@ static inline int pfn_section_valid(struct mem_section *ms, unsigned long pfn)
 static inline int pfn_valid(unsigned long pfn)
 {
 	struct mem_section *ms;
+	unsigned long sec_nr = pfn_to_section_nr(pfn);
 
-	if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
+	if (sec_nr >= NR_MEM_SECTIONS)
 		return 0;
-	ms = __nr_to_section(pfn_to_section_nr(pfn));
+	ms = __nr_to_section(sec_nr);
 	if (!valid_section(ms))
 		return 0;
 	/*

@@ -1374,9 +1375,11 @@ static inline int pfn_valid(unsigned long pfn)
 
 static inline int pfn_present(unsigned long pfn)
 {
-	if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
+	unsigned long sec_nr = pfn_to_section_nr(pfn);
+
+	if (sec_nr >= NR_MEM_SECTIONS)
 		return 0;
-	return present_section(__nr_to_section(pfn_to_section_nr(pfn)));
+	return present_section(__nr_to_section(sec_nr));
 }
 
 static inline unsigned long next_present_section_nr(unsigned long section_nr)
Signature · 1 line
1.9.1
Acked-by on v1 1/1
#1 lore raw
Quoted 33 lines

From: chenqiwu <[email protected]>

Remove duplicated pfn_to_section_nr() in pfn_valid() and pfn_present() to increase executing efficiency of code.

Signed-off-by chenqiwu <[email protected]>
---
 include/linux/mmzone.h | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)
include/linux/mmzone.h +3 -3
index 462f687..35763b5 100644
@@ -1358,10 +1358,11 @@ static inline int pfn_section_valid(struct mem_section *ms, unsigned long pfn)
 static inline int pfn_valid(unsigned long pfn)
 {
        struct mem_section *ms;
+       unsigned long sec_nr = pfn_to_section_nr(pfn);
 
-       if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
+       if (sec_nr >= NR_MEM_SECTIONS)
                return 0;
-       ms = __nr_to_section(pfn_to_section_nr(pfn));
+       ms = __nr_to_section(sec_nr);
        if (!valid_section(ms))
                return 0;
        /*

@@ -1374,9 +1375,11 @@ static inline int pfn_valid(unsigned long pfn)
 
 static inline int pfn_present(unsigned long pfn)
 {
-       if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)

include/linux/mmzone.h static inline int pfn_valid(unsigned long pfn)

Quoted 10 lines
include/linux/mmzone.h +4 -2
+       unsigned long sec_nr = pfn_to_section_nr(pfn);
+
+       if (sec_nr >= NR_MEM_SECTIONS)
                return 0;
-       return present_section(__nr_to_section(pfn_to_section_nr(pfn)));
+       return present_section(__nr_to_section(sec_nr));
 }
 
 static inline unsigned long next_present_section_nr(unsigned long section_nr)
--

Looks ok.

Acked-by Pankaj Gupta <[email protected]>
Quoted 3 lines

1.9.1

maintainer
#2 lore raw
In reply to [email protected]
Quoted 26 lines · On Mon, 16 Mar 2020 15:59:47 +0800 [email protected] wrote:

From: chenqiwu <[email protected]>

Remove duplicated pfn_to_section_nr() in pfn_valid() and pfn_present() to increase executing efficiency of code.

...

include/linux/mmzone.h +3 -2
@@ -1358,10 +1358,11 @@ static inline int pfn_section_valid(struct mem_section *ms, unsigned long pfn)
 static inline int pfn_valid(unsigned long pfn)
 {
 	struct mem_section *ms;
+	unsigned long sec_nr = pfn_to_section_nr(pfn);
 
-	if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
+	if (sec_nr >= NR_MEM_SECTIONS)
 		return 0;
-	ms = __nr_to_section(pfn_to_section_nr(pfn));
+	ms = __nr_to_section(sec_nr);
 	if (!valid_section(ms))
 		return 0;
 	/*

@@ -1374,9 +1375,11 @@ static inline int pfn_valid(unsigned long pfn)
 
 static inline int pfn_present(unsigned long pfn)

include/linux/mmzone.h static inline int pfn_valid(unsigned long pfn) · line 1384

Quoted 10 lines
include/linux/mmzone.h +4 -2
 {
-	if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
+	unsigned long sec_nr = pfn_to_section_nr(pfn);
+
+	if (sec_nr >= NR_MEM_SECTIONS)
 		return 0;
-	return present_section(__nr_to_section(pfn_to_section_nr(pfn)));
+	return present_section(__nr_to_section(sec_nr));
 }

The compiler already makes this optimization (pfn_to_section_nr() is very simple). Generated code appears to be identical.

I guess this patch could be sold as a cleanup, but I don't think it's worthwhile, really.