Re: Memory management in 2.6

[Michael Frank <mhf@xxxxxxxxxxxxx>]

I had already sent a version (ti-tests) dedicated to stress testing to LKML in October.

Just in case I enclose those again. README inside.

I ran 2.6 again for the first time since -test9 yesterday to test
swsusp and immeadiatly went to elevator=deadline as aio is unusable
at high io loads which I need to break swsusp in.

If you do on a 2GHz+ machine: 

$ti stat ub17 ddw 4 5000

This gives a load avg of ~40 on a 2.4G P4 with 533MHz FSB

2.4.23 behaves "proportionate" to load - at these loads mouse is jerky but has best throughput.

2.6 with deadline is similar but a bit slower and the mouse is very smooth.

2.6 with aio the mouse is smooth but no io throughput and io is highly intermittent. AFAICS similar to -test9.

It must be recognized that these tests act in a non-anticipatory manner - this is what they are designed for ;)

Regards
Michael

On Tuesday 20 January 2004 15:00, Nigel Cunningham wrote:
> 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.
>

ti-tests-1.0-beta-2.tar.bz2