Re: [PATCH] mm: page_alloc: Fix setting of ZONE_FAIR_DEPLETED on UP v2

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Mon, 8 Sep 2014 12:57:18 +0100 Mel Gorman <mgorman@xxxxxxx> wrote:

> zone_page_state is an API hazard because of the difference in behaviour
> between SMP and UP is very surprising. There is a good reason to allow
> NR_ALLOC_BATCH to go negative -- when the counter is reset the negative
> value takes recent activity into account. This patch makes zone_page_state
> behave the same on SMP and UP as saving one branch on UP is not likely to
> make a measurable performance difference.
> 
> ...
>
> --- a/include/linux/vmstat.h
> +++ b/include/linux/vmstat.h
> @@ -131,10 +131,8 @@ static inline unsigned long zone_page_state(struct zone *zone,
>  					enum zone_stat_item item)
>  {
>  	long x = atomic_long_read(&zone->vm_stat[item]);
> -#ifdef CONFIG_SMP
>  	if (x < 0)
>  		x = 0;
> -#endif
>  	return x;
>  }

We now have three fixes for the same thing.  I'm presently holding on
to hannes's mm-page_alloc-fix-zone-allocation-fairness-on-up.patch.

Regularizing zone_page_state() in this fashion seems a good idea and is
presumably safe because callers have been tested with SMP.  So unless
shouted at I think I'll queue this one for 3.18?

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>




[Index of Archives]     [Linux ARM Kernel]     [Linux ARM]     [Linux Omap]     [Fedora ARM]     [IETF Annouce]     [Bugtraq]     [Linux]     [Linux OMAP]     [Linux MIPS]     [ECOS]     [Asterisk Internet PBX]     [Linux API]