27.11.2010 00:38, Freddie Cash wrote: > On Fri, Nov 26, 2010 at 1:00 PM, Michael Tokarev <mjt@xxxxxxxxxx> wrote: [] >> Well, how about reading the changelog first, before asking? They're >> there for a reason, right? > > I read everything under /usr/share/doc/[qemu|kvm|libvirt], along with > the release notes on the qemu/kvm websites, and ended up with more > questions than answers, hence why I posted. :) I also read through a > bunch of old threads on the kvm mailing list, several bug reports for > qemu, qemu-kvm, libvirt, rhel, and so forth. No, I mean the changelog for the more recent debian packages. But it was more of a joke actually, please don't treat it too seriously. > The repeating theme through them all was that mem leaks in virtio > cropped up every other release or so, including some major ones in the > 0.12.x series (0.12.3 and 0.12.4 especially). The symptoms we're > having now are the same ones we originally had with KVM-72 when we > first switched from SCSI-emulated disks to virtio. qemu-kvm has a long history of bugs, that's true. That's why I kept 0.12 in Debian stable, instead of switching to 0.13. Lots of code, lots of new code too, difficult to have it bug-free from the beginning. Besides, maybe you hit yet another, still unknown bug of this theme - which is also a possibility ofcourse. No, kvm-0.12.5 (+ a few patches) is used to run guests in production, with quite some uptime too, and unlike with <=0.12.4, there were nothing wrong so far. >> Speaking of your setup, in addition to what Stephen said already, >> I'd strongly suggest considering hugepages - for this amount of >> memory hugepages should help quite alot, and this way you'll eliminate >> lots of pagetable entries. > > Hrm, I'll have to do some more googling on this. There's nothing > about it in the man pages or --help output, but I've seen it > references on the mailing list. Same for KSM (as suggested in another > message), although would that be helpful with such a variety of VM > guest OSes (Debian Etch, Debian Lenny, Ubuntu Server, Windows XP, > Windows 2003)? KSM may help, but it wont work with hugepages (since the more the page size is, the less chances to find another page with same contents). Hugepages - see -mem-path parameter. It's not widely known feature. The idea is that you allocate hugepages at boot, mount hugetlbfs, and give path to it in -mem-path, so that instead of malloc() kvm uses mmap() there. Or something of that theme. Hugepages are unswappable and unsharable (KSM), but they're much lighter in terms of pagetables and tlb misses. /mjt -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
