[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: [Xen-devel] Memory overhead of HVM domains
>From you definition of overhead, I think your overhead should include the >shadow page table, p2m table and those shadow cache, am I right? Not sure if any other sources. Also I just find a bug on qemu, which may occupy double size of the video memory if you are using Xwindow. Thanks Yunhong Jiang ---Original Message----- >From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx >[mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Charles Coffing >Sent: 2006年4月11日 12:43 >To: xen-devel@xxxxxxxxxxxxxxxxxxx >Subject: [Xen-devel] Memory overhead of HVM domains > >Hi, > >I was trying to find a solution for bug #521 ("video ram for hvm guests not >properly accounted for when ballooning"). The trivial (although ugly) answer >is to allocate an extra (hard-coded) 1026 pages in the getDomainMemory() >function to account for the increase_reservation that qemu-dm will do. > >However, ugly or not, this doesn't work. In reality, an HVM domain requires >some extra memory in addition to its nominal memory size. Here are some >measurements I did (everything in MB; overhead is approximate and measured by >looking at memory remaining in Xen's DMA and DOM memory zones before and after >creating the HVM domU): > >Nominal Overhead >------- -------- > 16 14.2 > 128 16.3 > 256 16.6 > 512 17.1 > 1024 18.4 > >4 MB of this is due to the VM's video memory. I expect additional state would >be stored in the qemu-dm process, but that would consume already-allocated dom0 >memory, and so wouldn't be represented above. I also see references to VMCBs >/ VMCSs, but those are getting allocated on Xen's heap, and so also not >represented above. > >So several questions: > >1. Where's the extra memory going? > >2. Should we even try to calculate it for auto-ballooning? It seems like many >factors could affect it, and any such calculation would be very brittle. > >I'll gladly code up and test a patch to auto-balloon for HVM domains, but I >first >want to understand what's going on. > >Thanks, >Chuck > > > >_______________________________________________ >Xen-devel mailing list >Xen-devel@xxxxxxxxxxxxxxxxxxx >http://lists.xensource.com/xen-devel _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
|
![]() |
Lists.xenproject.org is hosted with RackSpace, monitoring our |