linux-kernel - Re: [Xen-devel] Re: [PATCH R3 5/7] xen/balloon: Protect against CPU exhaust by event/x proces

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Date:	Sat, 12 Feb 2011 01:50:04 +0100
From:	Daniel Kiper <dkiper@...-space.pl>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc:	Daniel Kiper <dkiper@...-space.pl>, jeremy@...p.org,
	xen-devel@...ts.xensource.com, ian.campbell@...rix.com,
	haicheng.li@...ux.intel.com, linux-kernel@...r.kernel.org,
	dan.magenheimer@...cle.com, v.tolstov@...fip.ru,
	dave@...ux.vnet.ibm.com, linux-mm@...ck.org, rientjes@...gle.com,
	andi.kleen@...el.com, akpm@...ux-foundation.org,
	fengguang.wu@...el.com, wdauchy@...il.com
Subject: Re: [Xen-devel] Re: [PATCH R3 5/7] xen/balloon: Protect against CPU exhaust by event/x proces

On Thu, Feb 10, 2011 at 12:10:20PM -0500, Konrad Rzeszutek Wilk wrote:
> On Thu, Feb 10, 2011 at 10:51:42AM -0500, Konrad Rzeszutek Wilk wrote:
> > On Thu, Feb 03, 2011 at 05:28:51PM +0100, Daniel Kiper wrote:
> > > Protect against CPU exhaust by event/x process during
> > > errors by adding some delays in scheduling next event.
> > >
> > > Signed-off-by: Daniel Kiper <dkiper@...-space.pl>
> > > ---
> > >  drivers/xen/balloon.c |   99 +++++++++++++++++++++++++++++++++++++++---------
> > >  1 files changed, 80 insertions(+), 19 deletions(-)
> > >
> > > diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
> > > index 4223f64..ed103d4 100644
> > > --- a/drivers/xen/balloon.c
> > > +++ b/drivers/xen/balloon.c
> > > @@ -66,6 +66,20 @@
> > >
> > >  #define BALLOON_CLASS_NAME "xen_memory"
> > >
> > > +/*
> > > + * balloon_process() state:
> > > + *
> > > + * BP_ERROR: error, go to sleep,
> > > + * BP_DONE: done or nothing to do,
> > > + * BP_HUNGRY: hungry.
> > > + */
> > > +
> > > +enum bp_state {
> > > +	BP_ERROR,
> >
> > BP_EAGAIN?
> >
> > So if we fail to increase the first hour, we would keep on trying to
> > increase forever (with a 32 second delay between each call). Do you
> > think it makes sense (as a future patch, not tied in with this patchset)
> > to printout a printk(KERN_INFO that we have been trying to increase
> > for the last X hours, seconds and have not gone anywhere (and perhaps
> > stop trying to allocate more memory?).
>
> Duh, you did that in the next patch with the mh_policy.

No problem. You showed me that I could improve that. Thx.

Daniel
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