Re: [PATCH] xen: Fix selfballooning and ensure it doesn't go too far

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Sat, Sep 24, 2011 at 01:58:08PM -0700, Dan Magenheimer wrote:
> [PATCH] xen: Fix selfballooning and ensure it doesn't go too far
> 
> The balloon driver's "current_pages" is very different from
> totalram_pages.  Self-ballooning needs to be driven by
> the latter.  Also, Committed_AS doesn't account for pages
> used by the kernel so enforce a floor for when there
> are little or no user-space threads using memory.

Hey Dan,
..
> +		floor_pages = totalreserve_pages +
> +				(roundup_pow_of_two(max_pfn) >> 5);

Would it make sense to make the shift be a runtime argument
in case some users report problems with that calculation?

> +		/* don't balloon too far, lest OOMs occur... */
> +		if (tgt_pages < floor_pages)
> +			tgt_pages = floor_pages;
> +		balloon_set_new_target(tgt_pages +
> +			balloon_stats.current_pages - totalram_pages);
>  		reset_timer = true;
>  	}
>  #ifdef CONFIG_FRONTSWAP

Otherwise it looks OK to me. Would you like me to queue it up
for 3.1-rc7?