Re: [PATCH] micro optimization of cache_estimate in slab.c

[Pekka J Enberg <penberg@cs.Helsinki.FI>]

On Sun, 18 Dec 2005, Steven Rostedt wrote:
> Index: linux-2.6.15-rc5/mm/slab.c
> ===================================================================
> --- linux-2.6.15-rc5.orig/mm/slab.c	2005-12-16 16:24:09.000000000 -0500
> +++ linux-2.6.15-rc5/mm/slab.c	2005-12-18 13:30:13.000000000 -0500
> @@ -708,7 +708,14 @@
>  		base = sizeof(struct slab);
>  		extra = sizeof(kmem_bufctl_t);
>  	}
> -	i = 0;
> +	/*
> +	 * Divide the amount we have, by the amount we need for
> +	 * each object.  Since the size is already calculated
> +	 * to be no less than the alignment, this result will
> +	 * not be any greater than 1 that we need, and this will
> +	 * be subtracted after the while loop.
> +	 */
> +	i = (wastage - base)/(size + extra);
>  	while (i*size + ALIGN(base+i*extra, align) <= wastage)
>  		i++;
>  	if (i > 0)

Thanks. Looks much better but I am still wondering if we could get rid of 
the loop altogether. Hmm.

			Pekka
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