Re: Reducing inode cache usage on 2.4?

[Marcelo Tosatti <marcelo.tosatti@cyclades.com>]

James,

Can apply Andrew's patch and examine the results?

I've merged it to mainline because it looks sensible.

Thanks Andrew!

On Fri, Dec 17, 2004 at 05:21:04PM -0800, Andrew Morton wrote:
> James Pearson <james-p@moving-picture.com> wrote:
> >
> > It seems the inode cache has priority over cached file data.
> 
> It does.  If the machine is full of unmapped clean pagecache pages the
> kernel won't even try to reclaim inodes.  This should help a bit:
> 
> --- 24/mm/vmscan.c~a	2004-12-17 17:18:31.660254712 -0800
> +++ 24-akpm/mm/vmscan.c	2004-12-17 17:18:41.821709936 -0800
> @@ -659,13 +659,13 @@ int fastcall try_to_free_pages_zone(zone
>  
>  		do {
>  			nr_pages = shrink_caches(classzone, gfp_mask, nr_pages, &failed_swapout);
> -			if (nr_pages <= 0)
> -				return 1;
>  			shrink_dcache_memory(vm_vfs_scan_ratio, gfp_mask);
>  			shrink_icache_memory(vm_vfs_scan_ratio, gfp_mask);
>  #ifdef CONFIG_QUOTA
>  			shrink_dqcache_memory(vm_vfs_scan_ratio, gfp_mask);
>  #endif
> +			if (nr_pages <= 0)
> +				return 1;
>  			if (!failed_swapout)
>  				failed_swapout = !swap_out(classzone);
>  		} while (--tries);
> _
> 
> 
> >  What triggers the 'normal ageing round'? Is it possible to trigger this 
> >  earlier (at a lower memory usage), or give a higher priority to cached data?
> 
> You could also try lowering /proc/sys/vm/vm_mapped_ratio.  That will cause
> inodes to be reaped more easily, but will also cause more swapout.