From mboxrd@z Thu Jan 1 00:00:00 1970 From: Don Slutz Subject: Re: [PATCH v2 for-4.5] libxl: account for romfile memory Date: Wed, 26 Nov 2014 15:05:36 -0500 Message-ID: <54763290.4030104@terremark.com> References: <1416919412-10104-1-git-send-email-stefano.stabellini@eu.citrix.com> <1416925448.32327.27.camel@citrix.com> <1416934562.11944.22.camel@citrix.com> <1416994330.11944.25.camel@citrix.com> <1417007040.11944.50.camel@citrix.com> <20141126144040.GD8735@laptop.dumpdata.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20141126144040.GD8735@laptop.dumpdata.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: Konrad Rzeszutek Wilk Cc: xen-devel@lists.xensource.com, Wei Liu , Ian Campbell , Stefano Stabellini , Ian Jackson , Don Slutz , hanyandong List-Id: xen-devel@lists.xenproject.org On 11/26/14 09:40, Konrad Rzeszutek Wilk wrote: > On Wed, Nov 26, 2014 at 01:04:00PM +0000, Ian Campbell wrote: >> On Wed, 2014-11-26 at 12:39 +0000, Stefano Stabellini wrote: >>> On Wed, 26 Nov 2014, Ian Campbell wrote: >>>> On Tue, 2014-11-25 at 17:05 +0000, Stefano Stabellini wrote: >>>>> On Tue, 25 Nov 2014, Ian Campbell wrote: >>>>>> On Tue, 2014-11-25 at 16:49 +0000, Stefano Stabellini wrote: >>>>>>> On Tue, 25 Nov 2014, Ian Campbell wrote: >>>>>>>> On Tue, 2014-11-25 at 12:43 +0000, Stefano Stabellini wrote: >>>>>>>>> Account for the extra memory needed for the rom files of any emulated nics: >>>>>>>>> QEMU uses xc_domain_populate_physmap_exact to allocate the memory for >>>>>>>>> each them. Assume 256K each. >>>>>>>> I suppose this will have to do for 4.5. Can we do something better in >>>>>>>> the future -- like figuring out a way for guests to have >>>>>>>> "not-really-RAM" allocations like this which are made by the toolstack >>>>>>>> and happen to be backed by RAM not count or something. >>>>>>>> >>>>>>>>> This patch fixes a QEMU abort() when more than 4 emulated nics are >>>>>>>>> assigned to a VM. >>>>>>>> Are you also going to fix qemu to fail gracefully if it cannot deploy >>>>>>>> option roms? abort() seems a bit extreme. >>>>>>>> >>>>>>>>> Signed-off-by: Stefano Stabellini >>>>>>>>> CC: Don Slutz >>>>>>>>> CC: hanyandong >>>>>>>>> CC: Konrad Rzeszutek Wilk >>>>>>>>> CC: Ian Campbell >>>>>>>>> CC: Wei Liu >>>>>>>> You missed Ian J. I've added him. >>>>>>> Actually Wei suggested a better alternative: I could call >>>>>>> xc_domain_setmaxmem directly from QEMU. That makes much more sense. >>>>>> xl mem-set would do it again, but not taking qemu's extras into account, >>>>>> unless you communicate the overhead somehow... >>>>> We could start reading the current maxmem and add to it in >>>>> libxl_set_memory_target. Or we could write the maxmem to xenstore and >>>>> read it back again. Given that the allocations are only done by QEMU at >>>>> initialization time, I don't think we need to worry about concurrency >>>>> here. >>>> Might work, but it's a bit scary for 4.5, I would expect there to be >>>> subtle knock on effects from this sort of thing :-/ >>> >>> Given that this is not a regression, we could wait for 4.6 to commit the >>> fix and then if it doesn't cause any unwanted side effects, we could >>> backport it? >> That's not a bad plan. Release noting "you can't create more than 4 >> emulated NICs" doesn't seem so bad to me. The Release note needs to include that e1000 & rtl8139 have this restriction. vmxnet3 does not (and cannot be used for PXE boot). -Don Slutz > > > 4.6 it is then! >> Ian. >>