Re: Memory management in 2.6

[Nigel Cunningham <ncunningham@users.sourceforge.net>]

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Hi.

Michael Frank has written some scripts  we've used to stress test
software suspend. Perhaps you might be able to make some mileage from
them?

Regards,

Nigel

On Tue, 2004-01-20 at 17:51, Nick Piggin wrote:
> Hi,
> In the interest of helping improve 2.6 VM performance when
> under heavy swapping load, I'm putting together a few regression
> tests.
> 
> If anyone has any suggestions of workloads I could use, I will
> try to include them, or code them up if you want a simple concept
> tested. Also, any suggestions of what information I should gather?
> 
> loads should be runnable on about 64MB, preferably give decently
> repeatable results in under an hour.
> 
> I'll be happy to test patches. Here is one (results are a bit
> wild because it was only 1 run).
> 
> Nick
> 
> 
> ______________________________________________________________________
>  linux-2.6-npiggin/mm/vmscan.c |   30 +++++++++++++++++++++++-------
>  1 files changed, 23 insertions(+), 7 deletions(-)
> 
> diff -puN mm/vmscan.c~vm-akpm-balance-pgdat mm/vmscan.c
> --- linux-2.6/mm/vmscan.c~vm-akpm-balance-pgdat	2004-01-17 20:35:39.000000000 +1100
> +++ linux-2.6-npiggin/mm/vmscan.c	2004-01-17 20:35:42.000000000 +1100
> @@ -941,11 +941,12 @@ static int balance_pgdat(pg_data_t *pgda
>  			int nr_mapped = 0;
>  			int max_scan;
>  			int to_reclaim;
> +			int reclaimed;
>  
>  			if (zone->all_unreclaimable && priority != DEF_PRIORITY)
>  				continue;
>  
> -			if (nr_pages && to_free > 0) {	/* Software suspend */
> +			if (nr_pages && nr_pages > 0) {	/* Software suspend */
>  				to_reclaim = min(to_free, SWAP_CLUSTER_MAX*8);
>  			} else {			/* Zone balancing */
>  				to_reclaim = zone->pages_high-zone->free_pages;
> @@ -953,28 +954,43 @@ static int balance_pgdat(pg_data_t *pgda
>  					continue;
>  			}
>  			zone->temp_priority = priority;
> -			all_zones_ok = 0;
>  			max_scan = zone->nr_inactive >> priority;
>  			if (max_scan < to_reclaim * 2)
>  				max_scan = to_reclaim * 2;
>  			if (max_scan < SWAP_CLUSTER_MAX)
>  				max_scan = SWAP_CLUSTER_MAX;
> -			to_free -= shrink_zone(zone, max_scan, GFP_KERNEL,
> +			reclaimed = shrink_zone(zone, max_scan, GFP_KERNEL,
>  					to_reclaim, &nr_mapped, ps, priority);
>  			if (i < ZONE_HIGHMEM) {
>  				reclaim_state->reclaimed_slab = 0;
>  				shrink_slab(max_scan + nr_mapped, GFP_KERNEL);
> -				to_free -= reclaim_state->reclaimed_slab;
> +				reclaimed += reclaim_state->reclaimed_slab;
>  			}
> +			to_free -= reclaimed;
>  			if (zone->all_unreclaimable)
>  				continue;
>  			if (zone->pages_scanned > zone->present_pages * 2)
>  				zone->all_unreclaimable = 1;
> +			/*
> +			 * If this scan failed to reclaim `to_reclaim' or more
> +			 * pages, we're getting into trouble.  Need to scan
> +			 * some more, and throttle kswapd.   Note that this zone
> +			 * may now have sufficient free pages due to freeing
> +			 * activity by some other process.   That's OK - we'll
> +			 * pick that info up on the next pass through the loop.
> +			 */
> +			if (reclaimed < to_reclaim)
> +				all_zones_ok = 0;
>  		}
> -		if (all_zones_ok)
> -			break;
>  		if (to_free > 0)
> -			blk_congestion_wait(WRITE, HZ/10);
> +			continue;	/* swsusp: need to do more work */
> +		if (all_zones_ok)
> +			break;		/* kswapd: all done */
> +		/*
> +		 * OK, kswapd is getting into trouble.  Take a nap, then take
> +		 * another pass across the zones.
> +		 */
> +		blk_congestion_wait(WRITE, HZ/10);
>  	}
>  
>  	for (i = 0; i < pgdat->nr_zones; i++) {
> 
> _
-- 
My work on Software Suspend is graciously brought to you by
LinuxFund.org.

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