[PATCH] ul: enhance command performance

[PATCH] ul: enhance command performance

[Sami Kerola]

Avoid reseting, time after time, the memory which was not used.  Effect
of the change is below in before and after timings.

$ time ./ul </etc/services >/dev/null
real    0m0.320s
user    0m0.307s
sys     0m0.010s

$ time ./ul </etc/services >/dev/null
real    0m0.068s
user    0m0.050s
sys     0m0.017s

Signed-off-by: Sami Kerola <kerolasa@iki.fi>
---
 text-utils/ul.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/text-utils/ul.c b/text-utils/ul.c
index 5710a55..572f1b8 100644
--- a/text-utils/ul.c
+++ b/text-utils/ul.c
@@ -491,11 +491,11 @@ static void initbuf(void)
 	if (obuf == NULL) {
 		/* First time. */
 		obuflen = BUFSIZ;
-		obuf = xmalloc(sizeof(struct CHAR) * obuflen);
+		obuf = xcalloc(obuflen, sizeof(struct CHAR));
 	}
 
 	/* assumes NORMAL == 0 */
-	memset(obuf, 0, sizeof(struct CHAR) * obuflen);
+	memset(obuf, 0, sizeof(struct CHAR) * col);
 	setcol(0);
 	maxcol = 0;
 	mode &= ALTSET;
-- 
1.8.3.1

Re: [PATCH] ul: enhance command performance

[Karel Zak]

On Sun, Jun 30, 2013 at 09:44:00AM +0100, Sami Kerola wrote:
> Avoid reseting, time after time, the memory which was not used.  Effect
> of the change is below in before and after timings.
> 
> $ time ./ul </etc/services >/dev/null
> real    0m0.320s
> user    0m0.307s
> sys     0m0.010s
> 
> $ time ./ul </etc/services >/dev/null
> real    0m0.068s
> user    0m0.050s
> sys     0m0.017s

 Good catch :-)

> @@ -491,11 +491,11 @@ static void initbuf(void)
>  	if (obuf == NULL) {
>  		/* First time. */
>  		obuflen = BUFSIZ;
> -		obuf = xmalloc(sizeof(struct CHAR) * obuflen);
> +		obuf = xcalloc(obuflen, sizeof(struct CHAR));
>  	}
>  
    else

>  	/* assumes NORMAL == 0 */
> -	memset(obuf, 0, sizeof(struct CHAR) * obuflen);
> +	memset(obuf, 0, sizeof(struct CHAR) * col);

 I think 'maxcol' rather than col is more precise solution ;-) 

 Applied, thanks.

    Karel

-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com