Re: swapping and the value of /proc/sys/vm/swappiness

[Ray Bryant <raybry@sgi.com>]

Nick Piggin wrote:
> 
> 
> Nick Piggin wrote:
> 
>>
>> Thanks Ray. From looking over your old results, it appears that 
>> -kswapdfix
>> probably has the nicest swappiness ramp, which is probably to be 
>> expected,
>> as the problem that is being fixed did exist in all other kernels you 
>> tested,
>> but the later ones just had other aggrivating changes.
>>
>> The swappiness=60 weirdness might just be some obscure interaction 
>> with the
>> workload. If that is the case, it is probably not too important, 
>> however it
>> could be due to a possible oversight in my patch....
>>
> 
> Here is a patch on top of the last one - if you can give it a test
> some time, that would be great.
> 
> Thanks
> Nick
> 
> 

Nick,

I'll put it on my list of TODO's.  FYI, a full test like the ones I have been
running, at 6 swappiness levels, takes around 5 hours of machine time, so it
sometimes we have to wait for a slot that big to open up.  :-)

Ray
> ------------------------------------------------------------------------
> 
> 
> 
> 
> ---
> 
>  linux-2.6-npiggin/mm/vmscan.c |    9 +++++++--
>  1 files changed, 7 insertions(+), 2 deletions(-)
> 
> diff -puN mm/vmscan.c~vm-no-wild-kswapd2 mm/vmscan.c
> --- linux-2.6/mm/vmscan.c~vm-no-wild-kswapd2	2004-09-29 10:30:49.000000000 +1000
> +++ linux-2.6-npiggin/mm/vmscan.c	2004-09-29 10:34:00.000000000 +1000
> @@ -991,6 +991,7 @@ out:
>  static int balance_pgdat(pg_data_t *pgdat, int nr_pages)
>  {
>  	int to_free = nr_pages;
> +	int all_zones_ok;
>  	int priority;
>  	int i;
>  	int total_scanned, total_reclaimed;
> @@ -1013,10 +1014,11 @@ loop_again:
>  	}
>  
>  	for (priority = DEF_PRIORITY; priority >= 0; priority--) {
> -		int all_zones_ok = 1;
>  		int end_zone = 0;	/* Inclusive.  0 = ZONE_DMA */
>  		unsigned long lru_pages = 0;
>  
> +		all_zones_ok = 1;
> +
>  		if (nr_pages == 0) {
>  			/*
>  			 * Scan in the highmem->dma direction for the highest
> @@ -1106,7 +1108,7 @@ scan:
>  		 * on zone->*_priority.
>  		 */
>  		if (total_reclaimed >= SWAP_CLUSTER_MAX)
> -			goto loop_again;
> +			break;
>  	}
>  out:
>  	for (i = 0; i < pgdat->nr_zones; i++) {
> @@ -1114,6 +1116,9 @@ out:
>  
>  		zone->prev_priority = zone->temp_priority;
>  	}
> +	if (!all_zones_ok)
> +		goto loop_again;
> +
>  	return total_reclaimed;
>  }
>  
> 
> _


-- 
Best Regards,
Ray
-----------------------------------------------
                   Ray Bryant
512-453-9679 (work)         512-507-7807 (cell)
raybry@sgi.com             raybry@austin.rr.com
The box said: "Requires Windows 98 or better",
            so I installed Linux.
-----------------------------------------------