Date: Wed, 18 Sep 2002 23:54:24 +0200
From: Pavel Machek <pavel@suse.cz>
To: Andrew Morton <akpm@digeo.com>
Cc: lkml <linux-kernel@vger.kernel.org>,
       "linux-mm@kvack.org" <linux-mm@kvack.org>,
       "lse-tech@lists.sourceforge.net" <lse-tech@lists.sourceforge.net>
Subject: Re: 2.5.35-mm1
Message-ID: <20020918215424.GB2967@atrey.karlin.mff.cuni.cz>
References: <3D858515.ED128C76@digeo.com> <20020917160722.G39@toy.ucw.cz> <3D88F099.81A50A89@digeo.com>
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Hi!

> > > url: http://www.zip.com.au/~akpm/linux/patches/2.5/2.5.35/2.5.35-mm1/
> > >
> > > Significant rework of the new sleep/wakeup code - make it look totally
> > > different from the current APIs to avoid confusion, and to make it
> > > simpler to use.
> > 
> > Did you add any hooks to allow me to free memory for swsusp?
> 
> I just did then.  You'll need to call
> 
> 	freed = shrink_all_memory(99);

Thanx a lot.

> to free up 99 pages.  It returns the number which it actually
> freed.  If that's not 99 then it's time to give up.  There is
> no oom-killer in this code path.

So... I'll do something like shrink_all_memory(1000000) and it will
free as much as possible, right?

> I haven't tested it yet.  And it's quite a long way back in the
> queue I'm afraid - it has a dependency chain, and I prefer to

So if I apply this to my tree it will not work (that's what
"dependency chain means", right?). Okay, thanx anyway.

> send stuff to Linus which has been tested for a couple of weeks, and
> hasn't changed for one week.
> 
> Can you use the allocate-lots-then-free-it trick in the meanwhile?

In the meanwhile, swsusp only working when there's lot of ram is
probably okay. As IDE patch is not in, swsusp is dangerous, anyway.

									Pavel 

> --- 2.5.36/mm/vmscan.c~swsusp-feature	Wed Sep 18 13:55:20 2002
> +++ 2.5.36-akpm/mm/vmscan.c	Wed Sep 18 14:29:13 2002
> @@ -694,12 +694,19 @@ try_to_free_pages(struct zone *classzone
>  }
>  
>  /*
> - * kswapd will work across all this node's zones until they are all at
> - * pages_high.
> + * For kswapd, balance_pgdat() will work across all this node's zones until
> + * they are all at pages_high.
> + *
> + * If `nr_pages' is non-zero then it is the number of pages which are to be
> + * reclaimed, regardless of the zone occupancies.  This is a software suspend
> + * special.
> + *
> + * Returns the number of pages which were actually freed.
>   */
> -static void kswapd_balance_pgdat(pg_data_t *pgdat)
> +static int balance_pgdat(pg_data_t *pgdat, int nr_pages)
>  {
> -	int priority = DEF_PRIORITY;
> +	int to_free = nr_pages;
> +	int priority;
>  	int i;
>  
>  	for (priority = DEF_PRIORITY; priority; priority--) {
> @@ -712,13 +719,15 @@ static void kswapd_balance_pgdat(pg_data
>  			int to_reclaim;
>  
>  			to_reclaim = zone->pages_high - zone->free_pages;
> +			if (nr_pages && to_free > 0)
> +				to_reclaim = min(to_free, SWAP_CLUSTER_MAX*8);
>  			if (to_reclaim <= 0)
>  				continue;
>  			success = 0;
>  			max_scan = zone->nr_inactive >> priority;
>  			if (max_scan < to_reclaim * 2)
>  				max_scan = to_reclaim * 2;
> -			shrink_zone(zone, max_scan, GFP_KSWAPD,
> +			to_free -= shrink_zone(zone, max_scan, GFP_KSWAPD,
>  					to_reclaim, &nr_mapped);
>  			shrink_slab(max_scan + nr_mapped, GFP_KSWAPD);
>  		}
> @@ -726,6 +735,7 @@ static void kswapd_balance_pgdat(pg_data
>  			break;	/* All zones are at pages_high */
>  		blk_congestion_wait(WRITE, HZ/4);
>  	}
> +	return nr_pages - to_free;
>  }
>  
>  /*
> @@ -772,10 +782,34 @@ int kswapd(void *p)
>  		prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
>  		schedule();
>  		finish_wait(&pgdat->kswapd_wait, &wait);
> -		kswapd_balance_pgdat(pgdat);
> +		balance_pgdat(pgdat, 0);
>  		blk_run_queues();
>  	}
>  }
> +
> +#ifdef CONFIG_SOFTWARE_SUSPEND
> +/*
> + * Try to free `nr_pages' of memory, system-wide.  Returns the number of freed
> + * pages.
> + */
> +int shrink_all_memory(int nr_pages)
> +{
> +	pg_data_t *pgdat;
> +	int nr_to_free = nr_pages;
> +	int ret = 0;
> +
> +	for_each_pgdat(pgdat) {
> +		int freed;
> +
> +		freed = balance_pgdat(pgdat, nr_to_free);
> +		ret += freed;
> +		nr_to_free -= freed;
> +		if (nr_to_free <= 0)
> +			break;
> +	}
> +	return ret;
> +}
> +#endif
>  
>  static int __init kswapd_init(void)
>  {
> --- 2.5.36/include/linux/swap.h~swsusp-feature	Wed Sep 18 14:03:01 2002
> +++ 2.5.36-akpm/include/linux/swap.h	Wed Sep 18 14:16:29 2002
> @@ -163,6 +163,7 @@ extern void swap_setup(void);
>  
>  /* linux/mm/vmscan.c */
>  extern int try_to_free_pages(struct zone *, unsigned int, unsigned int);
> +int shrink_all_memory(int nr_pages);
>  
>  /* linux/mm/page_io.c */
>  int swap_readpage(struct file *file, struct page *page);
> 
> .

-- 
Casualities in World Trade Center: ~3k dead inside the building,
cryptography in U.S.A. and free speech in Czech Republic.
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