26.11.2010 22:19, Freddie Cash wrote: > Are there still known memory leaks in the virtio block and/or net > drivers? If not, have we found one? > > This is our host setup: > - Tyan h2000M motherboard > - 2x dual-core AMD Opteron 2220 CPUs > - 16 GB RAM > - quad-port NIC bonded together into 1 kvmbr0 interface > - 3Ware 9550SXU-12ML RAID controller > - 12x 400 GB SATA drives (4-disk RAID5, 4-disk RAID5, 3-disk RAID5, > spare disk) > - LVM used to stitch the 3 arrays into one volume group > > Running 64-bit Debian 5.0 (Lenny), using qemu-kvm0.12.4 and kernel > 2.6.32 from lenny-backports. There were some memleaks in i/o paths fixed in 0.12 series of kvm. In particular, 0.12.4 upstream version had a memory leak in virtio_blk, but that bug isn't present in 0.12.4+dfsg-1 - first 0.12.4 version as appeared in debian (the fix included upstream in 0.12.5). I know no other memleaks in later 0.12 series which aren't fixed in debian. > Guests are Ubuntu Server 8.04 LTS, Debian Lenny, Windows XP, and Windows 2003. For debian lenny guests using virtio, consider switching to backports 2.6.32 kernel too - lenny's 2.6.26 has several defects in virtio implementation. > All of the Linux VMs use virtio for both network and disk. > All the Windows VMs use virtio for network and IDE emulation for disk. > > Within 2 weeks of booting, the host machine is using 2 GB of swap, and > disk I/O wait is through the roof. Restarting all of the VMs will > free up RAM, but restarting the whole box is the only way to get > performance back up. > > A guest configured to use 8 GB of RAM will have 9 GB virt and 7.5 GB > res shown in top. In fact, every single VM shows virt above the limit > set for the VM. Usually by close to 25%. > > Going back through the mailing list archives and bug archives, there's > been mention of several memory leaks in the virtio drivers back to > KVM-72. Last bug report I read shows them all being fixed in 0.12.4, > which we're running. Yes, 0.12.4 had that bug, but it's fixed in 0.12.4+dfsg-1. The current version in backports is based on 0.12.5. > Perhaps there's something wrong with our setup? Perhaps there's still > a leak to be found? Perhaps this is fixed in 0.12.5 or newer? Well, how about reading the changelog first, before asking? They're there for a reason, right? 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. /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
