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Date: Thu, 06 Mar 2014 01:24:09 -0500 From: Brian Wong <draconicpenguin1@...oo.com> To: linux-kernel@...r.kernel.org Subject: Re: Linux does not use more than the startup RAM under Hyper-V with dynamic memory enabled On 3/6/2014 1:20 AM, Brian Wong wrote: > I'm new to LKML, so please don't be too hard on me :) > > I'm running Gentoo Linux under Microsoft Client Hyper-V on Windows 8.1 > Pro, and I've noticed some odd behavior with respect to dynamic memory > (aka memory ballooning). The system will never use more than the startup > memory defined in the vitual machine's settings. > > For example, if I set the startup memory to 512 MB, and enable dynamic > memory with a minimum of 512 MB and a maximum of 8192 MB, the system > will never allocate than 512 MB of physical memory, despite Hyper-V > assigning more memory to the VM and the added memory being visible in > the output of "free" and "htop". Attempting to use more memory causes > the system to start paging to swap, rather than actually allocating the > memory above the startup memory assigned to the VM. > > The kernel is built with the full set of Hyper-V drivers, including the > key "Microsoft Hyper-V Balloon Driver" as well as memory hot-add and > hot-remove functionality. This is happening with both the Gentoo-patched > 3.10.32 kernel and the vanilla 3.12.5 kernel. The host machine has a > total of 24 GB of memory. > > For now, I am working around the issue by starting the VM with the > startup memory set to the maximum and letting Hyper-V take the usused > memory back when it is not in use. The VM will then get the extra memory > when it needs it. > > Have I encountered a bug in the Hyper-V balloon driver? > Just a correction: the vanilla kernel version is 3.13.5, not 3.12.5. Sorry for any confusion. -- Brian Wong http://www.fierydragonlord.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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