Re: [Qemu-devel] Qemu and heavily increased RSS usage

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Peter Lieven (pl@kamp.de) wrote:
> Hi,
> 
> while upgrading from Qemu 2.2.0 to Qemu 2.5.1.1 I noticed that the RSS memory usage has heavily increased.
> We use hugepages so the RSS memory does not include VM memory. In Qemu 2.2.0 it used to be ~30MB per vServer
> and increased to up to 300 - 400MB for Qemu 2.5.1.1 (same with master). The memory increases over time, but seems
> not to grow indefinetly. I tried to bisect, but had no result so far that made sense. I also tried valgrind / massif, but
> valgrind does not see the allocation (at least at exit) and massif fails to rund due to - so it pretends - heap corruption.
> 
> Any help or ideas how to debug further would be appreciated.

I think I'd try stripping devices off; can you get a similar difference
to happen with a guest with no USB, no hugepages, no VGA and a simple
locally stored IDE disk?

If you're having trouble bisecting is it possible it's a change
in one of the libraries it's linked against?

There was someone asking the other day on #qemu who had a setup that
was apparently using much more RAM than expected and we didn't
manage to track it down but I can't remember the version being used.

Dave

> 
> Cmdline is:
> ./x86_64-softmmu/qemu-system-x86_64 -enable-kvm -M pc-i440fx-2.1 -nodefaults
> -netdev type=tap,id=guest3,script=no,downscript=no,ifname=tap0,vnet_hdr
> -device virtio-net-pci,netdev=guest3,mac=52:54:00:ff:08:5e -iscsi
> initiator-name=iqn.2005-03.org.xx:0025b5d0011f -drive format=raw,discard=on,file=iscsi://172.21.200.56/iqn.2001-05.com.equallogic:0-8a0906-98f384e0a-7d2004ee0a85767a-00lieven-test/0,if=none,cache=writeback,aio=native,id=disk0
> -object iothread,id=iothread0 -device
> virtio-blk-pci,drive=disk0,iothread=iothread0 -global
> virtio-blk-pci.scsi=off -serial null -parallel null -m 4096 -smp
> 4,sockets=1,cores=4,threads=1 -monitor tcp:0:4004,server,nowait,nodelay -qmp
> tcp:0:3004,server,nowait,nodelay -name lieven-test -boot
> order=c,once=dc,menu=off -k de -mem-path /hugepages -mem-prealloc -cpu
> Westmere,enforce -rtc base=utc -usb -usbdevice tablet -no-hpet -vga vmware
> 
> Thanks,
> Peter
> 
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK