VMware Balloon driver
in [Kernel]
|
From: Avi Kivity on 6 Apr 2010 14:40 On 04/06/2010 09:25 PM, Jeremy Fitzhardinge wrote: > On 04/06/2010 09:32 AM, Avi Kivity wrote: >> Yeah. If we wanted commonality, we could make a balloon_core.c that >> contains the common code. IMO that's premature, but perhaps there's >> some meat there (like suspend/resume support and /proc//sys interface). > > I think it would be useful to have common: > > 1. User and kernel mode ABIs for controlling ballooning. It assumes > that the different balloon implementations are sufficiently > similar in semantics. (Once there's a kernel ABI, adding a > common user ABI is trivial.) > 2. Policy driving the ballooning driver, at least from the guest > side. That is, some good metrics from the vm subsystem about > memory pressure (both positive and negative), and something to > turn those metrics into requests to the balloon driver. > > 1) is not a huge amount of code, but something consistent would be > nice. 2) is something we've been missing and is a bit of an open > question/research project anyway. 3) Code that attempts to reclaim 2MB pages when possible -- Do not meddle in the internals of kernels, for they are subtle and quick to panic. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Jeremy Fitzhardinge on 6 Apr 2010 15:20 On 04/06/2010 11:36 AM, Avi Kivity wrote: > On 04/06/2010 09:25 PM, Jeremy Fitzhardinge wrote: >> On 04/06/2010 09:32 AM, Avi Kivity wrote: >>> Yeah. If we wanted commonality, we could make a balloon_core.c that >>> contains the common code. IMO that's premature, but perhaps there's >>> some meat there (like suspend/resume support and /proc//sys interface). >> >> I think it would be useful to have common: >> >> 1. User and kernel mode ABIs for controlling ballooning. It assumes >> that the different balloon implementations are sufficiently >> similar in semantics. (Once there's a kernel ABI, adding a >> common user ABI is trivial.) >> 2. Policy driving the ballooning driver, at least from the guest >> side. That is, some good metrics from the vm subsystem about >> memory pressure (both positive and negative), and something to >> turn those metrics into requests to the balloon driver. >> >> 1) is not a huge amount of code, but something consistent would be >> nice. 2) is something we've been missing and is a bit of an open >> question/research project anyway. > > 3) Code that attempts to reclaim 2MB pages when possible Yes. Ballooning in 4k units is a bit silly. J -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Dave Hansen on 6 Apr 2010 19:30 On Mon, 2010-04-05 at 16:28 -0700, Jeremy Fitzhardinge wrote: > I guess a way to use it in the short term is to have a loop of the form: > > while (guest_size> target) { > shrink_all_memory(guest_size - target); /* force pages to be free */ > while (p = alloc_page(GFP_NORETRY)) /* vacuum up pages */ > release_page_to_hypervisor(p); > /* twiddle thumbs */ > } We also need to remember to consolidate the Xen and virtio-balloon drivers. They both have their own GFP flags, for instance, but I think they actually want the exact same thing. They could probably also share that snippet, right? -- Dave -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Pavel Machek on 8 Apr 2010 01:40 Hi! >>> 1) is not a huge amount of code, but something consistent would be >>> nice. 2) is something we've been missing and is a bit of an open >>> question/research project anyway. >> >> 3) Code that attempts to reclaim 2MB pages when possible > > Yes. Ballooning in 4k units is a bit silly. Does it make sense to treat ballooning as a form of memory hotplug? -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Avi Kivity on 8 Apr 2010 03:20
On 04/08/2010 08:30 AM, Pavel Machek wrote: > Hi! > > >>>> 1) is not a huge amount of code, but something consistent would be >>>> nice. 2) is something we've been missing and is a bit of an open >>>> question/research project anyway. >>>> >>> 3) Code that attempts to reclaim 2MB pages when possible >>> >> Yes. Ballooning in 4k units is a bit silly. >> > Does it make sense to treat ballooning as a form of memory hotplug? > It's a fine granularity form of memory hotplug, yes. -- error compiling committee.c: too many arguments to function -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |