Re: [libvirt] Problem with setting up KVM guests to use HugePages

2015-06-10 Thread Vivi L 
Michal Privoznik  redhat.com> writes:

> 
> On 10.06.2015 01:05, Vivi L wrote:
> > Kashyap Chamarthy  redhat.com> writes:
> > 
> > 
> >> You might want re-test by explicitly setting the 'page' element and
> >> 'size' attribute? From my test, I had something like this:
> >>
> >> $ virsh dumpxml f21-vm | grep hugepages -B3 -A2 
> >>   2000896
> >>   200
> >>   
> >> 
> >>   
> >> 
> >>   
> >>   8
> >>
> >> I haven't tested this exhaustively, but some basic test notes here:
> >>
> >> https://kashyapc.fedorapeople.org/virt/test-hugepages-with-libvirt.txt
> > 
> > Current QEMU does not support setting  element. Could it be the 
> > cause of my aforementioned problem?
> > 
> > unsupported configuration: huge pages per NUMA node are not supported 
> > with this QEMU
> > 
> 
> So this is explanation why the memory for you guest is not backed by
> hugepages.

I thought setting hugepages per NUMA node is a nice-to-have feature. 
Is it required to enable the use of hugepages for the guest? 
 
> Can you please share the qemu command line that libvirt generated for
> your guest?

If setting 100 hugepages, the guest can start while not using hugepages 
at all. In this case,
[root@local ~]# ps -ef | grep qemu
qemu  3403 1 99 17:42 ?00:36:42 /usr/libexec/qemu-kvm -name 
qvpc-di-03-sf -S -machine pc-i440fx-rhel7.0.0,accel=kvm,usb=off -cpu host 
-m 131072 -realtime mlock=off -smp 32,sockets=2,cores=16,threads=1 
-numa node,nodeid=0,cpus=0-15,mem=65536 -numa node,nodeid=1,
cpus=16-31,mem=65536 -uuid e1b72349-4a0b-4b91-aedc-fd34e92251e4 -
smbios type=1,serial=SCALE-SLOT-03 -no-user-config -nodefaults -chardev 
socket,id=charmonitor,path=/var/lib/libvirt/qemu/qvpc-di-03-sf.monitor,server,
nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc 
-no-shutdown -boot strict=on -device piix3-usb-uhci,id=usb,bus=pci.0,
addr=0x1.0x2 -drive file=/var/lib/libvirt/images/asr5700/qvpc-di-03-sf-
hda.img,if=none,id=drive-ide0-0-0,format=qcow2 -device ide-
hd,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0,bootindex=2 -drive 
if=none,id=drive-ide0-1-0,readonly=on,format=raw -device ide-
cd,bus=ide.1,unit=0,drive=drive-ide0-1-0,id=ide0-1-0,bootindex=1 -chardev 
pty,id=charserial0 -device isa-serial,chardev=charserial0,id=serial0 -chardev 
pty,id=charserial1 -device isa-serial,chardev=charserial1,id=serial1 
-vnc 127.0.0.1:0 -vga cirrus -device i6300esb,id=watchdog0,bus=pci.0,
addr=0x3 -watchdog-action reset -device 
vfio-pci,host=08:00.0,id=hostdev0,bus=pci.0,addr=0x5 -device vfio-
pci,host=09:00.0,id=hostdev1,bus=pci.0,addr=0x6 -device vfio-
pci,host=0a:00.0,id=hostdev2,bus=pci.0,addr=0x7 -device virtio-balloon-
pci,id=balloon0,bus=pci.0,addr=0x4 -msg timestamp=on


> Michal
> 
> 



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Re: [libvirt] Problem with setting up KVM guests to use HugePages

2015-06-09 Thread Vivi L 
Kashyap Chamarthy  redhat.com> writes:


> You might want re-test by explicitly setting the 'page' element and
> 'size' attribute? From my test, I had something like this:
> 
> $ virsh dumpxml f21-vm | grep hugepages -B3 -A2 
>   2000896
>   200
>   
> 
>   
> 
>   
>   8
> 
> I haven't tested this exhaustively, but some basic test notes here:
> 
> https://kashyapc.fedorapeople.org/virt/test-hugepages-with-libvirt.txt

Current QEMU does not support setting  element. Could it be the 
cause of my aforementioned problem?

unsupported configuration: huge pages per NUMA node are not supported 
with this QEMU




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[libvirt] Problem with setting up KVM guests to use HugePages

2015-06-09 Thread Vivi L 
Configure hugepages and then start virtual guest via "virsh start". However, 
virtual guest failed to use hugepages although it's configured

The initial usage of system memory
[root@local ~]# free
totalusedfree  shared  buff/cache   available
Mem:   263767352  1900628  261177892  9344688832   261431872
Swap:   4194300   0 4194300

After configuring hugepages, 
[root@local ~]# cat /proc/meminfo | grep uge
AnonHugePages:  2048 kB
HugePages_Total: 140
HugePages_Free:  140
HugePages_Rsvd:0
HugePages_Surp:0
Hugepagesize:1048576 kB

[root@local ~]# mount | grep huge
cgroup on /sys/fs/cgroup/hugetlb type cgroup (rw,nosuid,nodev,noexec,
relatime,hugetlb)hugetlbfs on /dev/hugepages type hugetlbfs (rw,realtime)

On the guest side, its config xml contains

  test-01
  e1b72349-4a0b-4b91-aedc-fd34e92251e4
  test-01
  134217728
  134217728
  


  


Tried to virsh start the guest, but it failed although the hugepages memory 
was sufficient
virsh # start test-01
error: Failed to start domain test-01
error: internal error: early end of file from monitor: possible problem:
Cannot set up guest memory 'pc.ram': Cannot allocate memory


however, if decrease the number of hugepages to smaller(say 100) that 
makes the memory not used by hugepages more than required by guest, 
then guest can start. But memory is not allocated from hugepages. 
[root@local ~]# cat /proc/meminfo | grep uge
AnonHugePages:  134254592 kB
HugePages_Total: 100
HugePages_Free:  100
HugePages_Rsvd:0
HugePages_Surp:0
Hugepagesize:1048576 kB

In summary, although hugepages is configured, the guest seemed not 
instructed to use hugepage, instead, the guest is allocated memory from 
the memory pool leftover by hugepages. 




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