[PATCH] swsusp: simpler calculation of number of pages in PBE list

[PATCH] swsusp: simpler calculation of number of pages in PBE list

[Pavel Machek]

From: Michal Schmidt <xschmi00@stud.feec.vutbr.cz>

The function calc_nr uses an iterative algorithm to calculate the
number of pages needed for the image and the pagedir. Exactly the same
result can be obtained with a one-line expression.

Note that this was even proved correct ;-).

Signed-off-by: Michal Schmidt <xschmi00@stud.feec.vutbr.cz>
Signed-off-by: Pavel Machek <pavel@suse.cz>

---
commit 06695555bdbe1a5ac3b7926867abfdc9e560121f
tree 3be140250bf556a51261ea75b908906e64182ec3
parent 42b960c2ed61b623d5e84b67f95c7f0ddad0565f
author <pavel@amd.(none)> Sat, 30 Jul 2005 15:19:56 +0200
committer <pavel@amd.(none)> Sat, 30 Jul 2005 15:19:56 +0200

 kernel/power/swsusp.c |   13 +------------
 1 files changed, 1 insertions(+), 12 deletions(-)

diff --git a/kernel/power/swsusp.c b/kernel/power/swsusp.c
--- a/kernel/power/swsusp.c
+++ b/kernel/power/swsusp.c
@@ -591,18 +591,7 @@ static void copy_data_pages(void)
 
 static int calc_nr(int nr_copy)
 {
-	int extra = 0;
-	int mod = !!(nr_copy % PBES_PER_PAGE);
-	int diff = (nr_copy / PBES_PER_PAGE) + mod;
-
-	do {
-		extra += diff;
-		nr_copy += diff;
-		mod = !!(nr_copy % PBES_PER_PAGE);
-		diff = (nr_copy / PBES_PER_PAGE) + mod - extra;
-	} while (diff > 0);
-
-	return nr_copy;
+	return nr_copy + (nr_copy+PBES_PER_PAGE-2)/(PBES_PER_PAGE-1);
 }
 
 /**

-- 
teflon -- maybe it is a trademark, but it should not be.

[PATCH] swsusp: simpler calculation of number of pages in PBE list

[Michal Schmidt]

[-- Attachment #1: Type: text/plain, Size: 251 bytes --]

The function calc_nr uses an iterative algorithm to calculate the number 
of pages needed for the image and the pagedir. Exactly the same result 
can be obtained with a one-line expression.

Signed-off-by: Michal Schmidt <xschmi00@stud.feec.vutbr.cz>

[-- Attachment #2: swsusp-simpler-calc_nr.diff --]
[-- Type: text/x-patch, Size: 690 bytes --]

diff -Nurp -X dontdiff.new linux-mm/kernel/power/swsusp.c linux-mm.mich/kernel/power/swsusp.c
--- linux-mm/kernel/power/swsusp.c	2005-07-28 13:57:53.000000000 +0200
+++ linux-mm.mich/kernel/power/swsusp.c	2005-07-29 21:01:46.000000000 +0200
@@ -737,18 +737,7 @@ static void copy_data_pages(void)
 
 static int calc_nr(int nr_copy)
 {
-	int extra = 0;
-	int mod = !!(nr_copy % PBES_PER_PAGE);
-	int diff = (nr_copy / PBES_PER_PAGE) + mod;
-
-	do {
-		extra += diff;
-		nr_copy += diff;
-		mod = !!(nr_copy % PBES_PER_PAGE);
-		diff = (nr_copy / PBES_PER_PAGE) + mod - extra;
-	} while (diff > 0);
-
-	return nr_copy;
+	return nr_copy + (nr_copy+PBES_PER_PAGE-2)/(PBES_PER_PAGE-1);
 }
 
 /**

Re: [PATCH] swsusp: simpler calculation of number of pages in PBE list

[Pavel Machek]

On Pá 29-07-05 21:46:40, Michal Schmidt wrote:
> The function calc_nr uses an iterative algorithm to calculate the number 
> of pages needed for the image and the pagedir. Exactly the same result 
> can be obtained with a one-line expression.
> 
> Signed-off-by: Michal Schmidt <xschmi00@stud.feec.vutbr.cz>

Thanks, applied.

> diff -Nurp -X dontdiff.new linux-mm/kernel/power/swsusp.c linux-mm.mich/kernel/power/swsusp.c
> --- linux-mm/kernel/power/swsusp.c	2005-07-28 13:57:53.000000000 +0200
> +++ linux-mm.mich/kernel/power/swsusp.c	2005-07-29 21:01:46.000000000 +0200
> @@ -737,18 +737,7 @@ static void copy_data_pages(void)
>  
>  static int calc_nr(int nr_copy)
>  {
> -	int extra = 0;
> -	int mod = !!(nr_copy % PBES_PER_PAGE);
> -	int diff = (nr_copy / PBES_PER_PAGE) + mod;
> -
> -	do {
> -		extra += diff;
> -		nr_copy += diff;
> -		mod = !!(nr_copy % PBES_PER_PAGE);
> -		diff = (nr_copy / PBES_PER_PAGE) + mod - extra;
> -	} while (diff > 0);
> -
> -	return nr_copy;
> +	return nr_copy + (nr_copy+PBES_PER_PAGE-2)/(PBES_PER_PAGE-1);
>  }
>  
>  /**


-- 
teflon -- maybe it is a trademark, but it should not be.