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Date: Mon, 26 Sep 2011 13:23:07 -0400
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: Dan Magenheimer <dan.magenheimer@oracle.com>
Cc: linux-kernel@vger.kernel.org, xen-devel@lists.xensource.com,
        David Vrabel <david.vrabel@citrix.com>,
        Jeremy Fitzhardinge <jeremy@goop.org>
Subject: Re: [PATCH] xen: Fix selfballooning and ensure it doesn't go too far
Message-ID: <20110926172307.GA9973@phenom.oracle.com>
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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?