[PATCH] mm/slab.c, kernel <2.4.20>

[Shangc]

/**
 * --readme--
 * make a better initial value for i, which will
reduce the number of 
while loop.
 * the change can be proved mathematically:
 *
 * i*size + L1_CACHE_ALIGN(base+i*extra) <= wastage
 * ==> i*size + base + i*extra <= wastage
 * ==> solve about equation about i
 * ==> i <= (wastage - base) / (size + extra)
 *
 * Chen Shang
 * [e-mail]
 */

--- slab.c	2003-02-08 04:26:50.000000000 -0500
+++ slab.c	2003-02-08 04:26:14.000000000 -0500
@@ -397,7 +397,7 @@
 		base = sizeof(slab_t);
 		extra = sizeof(kmem_bufctl_t);
 	}
-	i = 0;
+	i = (wastage - base) / (size + extra);
 	while (i*size + L1_CACHE_ALIGN(base+i*extra) <=
wastage)
 		i++;
 	if (i > 0)

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