Re: [PATCH] mm: swap prefetch fix lowmem reserve calc

[Nick Piggin <nickpiggin@yahoo.com.au>]

Con Kolivas wrote:
> When examining the free limits in swap_prefetch we should ensure the largest
> lowmem_reserve for each zone is free.
> 
> Signed-off-by: Con Kolivas <kernel@kolivas.org>
> 
> ---
>  mm/swap_prefetch.c |   14 +++++++++++++-
>  1 files changed, 13 insertions(+), 1 deletion(-)
> 
> Index: linux-2.6.17-rc4-mm1/mm/swap_prefetch.c
> ===================================================================
> --- linux-2.6.17-rc4-mm1.orig/mm/swap_prefetch.c	2006-05-18 15:48:22.000000000 +1000
> +++ linux-2.6.17-rc4-mm1/mm/swap_prefetch.c	2006-05-18 15:52:42.000000000 +1000
> @@ -258,6 +258,18 @@ static void clear_current_prefetch_free(
>  	}
>  }
>  
> +static inline unsigned long largest_lowmem_reserve(struct zone *z)
> +{
> +	unsigned long ret = 0;
> +	unsigned int idx = zone_idx(z);
> +
> +	while (!is_highmem_idx(idx)) {
> +		idx++;
> +		ret = max(ret, z->lowmem_reserve[idx]);
> +	}
> +	return ret;
> +}
> +
>  /*
>   * This updates the high and low watermarks of amount of free ram in each
>   * node used to start and stop prefetching. We prefetch from pages_high * 4
> @@ -276,7 +288,7 @@ static void examine_free_limits(void)
>  
>  		ns = &sp_stat.node[z->zone_pgdat->node_id];
>  		idx = zone_idx(z);
> -		ns->lowfree[idx] = z->pages_high * 3 + z->lowmem_reserve[idx];
> +		ns->lowfree[idx] = z->pages_high * 3 + largest_lowmem_reserve(z);
>  		ns->highfree[idx] = ns->lowfree[idx] + z->pages_high;

Anonymous memory is GFP_HIGHUSER, yeah? Anything wrong with

-		ns->lowfree[idx] = z->pages_high * 3 + z->lowmem_reserve[idx];
+		ns->lowfree[idx] = z->pages_high * 3 + z->lowmem_reserve[ZONE_HIGHMEM];


-- 
SUSE Labs, Novell Inc.
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