From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gedalya Subject: Re: [PATCH for-4.5 v2] libxc: don't leak buffer containing the uncompressed PV kernel Date: Fri, 21 Nov 2014 15:25:00 -0500 Message-ID: <546F9F9C.5090507@gedalya.net> References: <1416498527-32441-1-git-send-email-ian.campbell@citrix.com> <20141120202114.GE31889@laptop.dumpdata.com> <546EADD0.8010002@gedalya.net> <1416567797.26869.18.camel@citrix.com> <1416568333.26869.22.camel@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1416568333.26869.22.camel@citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Ian Campbell , Konrad Rzeszutek Wilk Cc: ian.jackson@eu.citrix.com, 767295@bugs.debian.org, wei.liu2@citrix.com, xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org On 11/21/2014 06:12 AM, Ian Campbell wrote: > On Fri, 2014-11-21 at 11:03 +0000, Ian Campbell wrote: >> http://man7.org/linux/man-pages/man3/mallopt.3.html also talks about >> various dynamic thresholds for growing and shrinking the heap. My guess >> is that we are bouncing up and down over some threshold with every other >> reboot. > IOW I'm not overly concerned with this apparent bi-modality, so long as > the amount isn't increasing in the long term... > > I think the original patch should go in. > > Ian. > > It's an improvement, but consider this: Someone has a xen host running wheezy, 40 domu's, with 768MB for dom0, worked fine so far. Tries upgrading to jessie, and lo, each domu process takes up only 588 KB on dom0, great! Then a new kernel package is released, all domu's get rebooted once. All host memory is now full. Dude might have had other plans for that memory... This is dead memory so I guess it can be swapped out, not easily a scenario where the server totally crashes, but it's a bit ugly, we're talking about memory usage leaping from 0.6 to 16 MB per domu.