Bug 680190

Too small value is given for "swap hard limit".

virsh # start test
Domain test started

virsh # memtune test
hard_limit     : unlimited
soft_limit     : unlimited
swap_hard_limit: unlimited

virsh # memtune test --hard-limit 1024000

virsh # memtune test --swap-hard-limit 1023000
error: Unable to change memory parameters
error: unable to set swap_hard_limit tunable: Invalid argument

virsh # memtune test --swap-hard-limit 1024000

virsh # memtune test --swap-hard-limit 1024001

virsh # memtune test
hard_limit     : 1024000 kB
soft_limit     : unlimited
swap_hard_limit: 1024004 kB

virsh # memtune test --swap-hard-limit 1023999

virsh # memtune test
hard_limit     : 1024000 kB
soft_limit     : unlimited
swap_hard_limit: 1024000 kB

NB, 1024001 is rounded up to 1024004, 1023999 is rounded up to 1024000.

I beleive if you set value of "<swap_hard_limit>" smaller than of "<hard_limit>", same error will be raised up.

Note that "memsw" means "memory+swap", so, somehow it's NOTABUG, but probly we need doc improvements.

upstream 78ba748ef1 fix the document problem.

The upstream commit

commit 78ba748ef14c520ff1c4af2b5b0a44586ac49c8c
Author: Nikunj A. Dadhania <nikunj.ibm.com>
Date:   Wed Mar 16 10:37:12 2011 +0530

    virsh: fix memtune's help message for swap_hard_limit

is incomplete and needs a follow-up patch.

The follow-up patch has been sent upstream: https://www.redhat.com/archives/libvir-list/2011-March/msg01506.html

POST: http://post-office.corp.redhat.com/archives/rhvirt-patches/2011-April/msg00003.html

# virsh memtune rhel6_x86_64_kvm
error: Unable to get number of memory parameters
error: this function is not supported by the connection driver: qemuDomainGetMemoryParameters


Current kvm hypervisor doesn't support the function, Is this a expected result? 

Additional info:

# virsh list 
 Id Name                 State
----------------------------------
  2 rhel6_x86_64_kvm     running

# virsh dominfo rhel6_x86_64_kvm
Id:             2
Name:           rhel6_x86_64_kvm
UUID:           82092589-bce2-6e75-ecd4-d0ffa9e36651
OS Type:        hvm
State:          running
CPU(s):         1
CPU time:       37.1s
Max memory:     524288 kB
Used memory:    524288 kB
Persistent:     yes
Autostart:      disable
Security model: selinux
Security DOI:   0
Security label: system_u:system_r:svirt_t:s0:c17,c124 (enforcing)

# uname -r
2.6.32-130.el6.x86_64

# rpm -q qemu-kvm
qemu-kvm-0.12.1.2-2.153.el6.x86_64

# rpm -q libvirt
libvirt-0.8.7-16.el6.x86_64

No, that's not expected. Are you sure you are running the right libvirtd version? virsh memtune works as expected for me with the latest
libvirt-0.8.7-17.el6 package.

(In reply to comment #8)
> No, that's not expected. Are you sure you are running the right libvirtd
> version? virsh memtune works as expected for me with the latest
> libvirt-0.8.7-17.el6 package.

Hi Jiri,
I saw 'Fixed In Version: libvirt-0.8.7-16.el6' on the right top, so I used -16 version to verify the bug, please update 'Fixed In Version' for the bug.

And will use -17 to verify the bug again.

Alex

The bug has been verified on rhel6.1 snapshot3(2.6.32-130.el6.x86_64) with libvirt-0.8.7-17.el6.x86_64.

# virsh start rhel6_x86_64_kvm
Domain rhel6_x86_64_kvm started

# virsh memtune rhel6_x86_64_kvm
hard_limit     : unlimited
soft_limit     : unlimited
swap_hard_limit: unlimited

# virsh memtune rhel6_x86_64_kvm --hard-limit 1024000

# virsh memtune rhel6_x86_64_kvm
hard_limit     : 1024000 kB
soft_limit     : unlimited
swap_hard_limit: unlimited


# virsh memtune rhel6_x86_64_kvm --swap-hard-limit 1024000

# virsh memtune rhel6_x86_64_kvm
hard_limit     : 1024000 kB
soft_limit     : unlimited
swap_hard_limit: 1024000 kB

# virsh memtune rhel6_x86_64_kvm --swap-hard-limit 1024001

[root@localhost Libvirt]# virsh memtune rhel6_x86_64_kvm
hard_limit     : 1024000 kB
soft_limit     : unlimited
swap_hard_limit: 1024004 kB

# virsh memtune rhel6_x86_64_kvm --swap-hard-limit 1023999

# virsh memtune rhel6_x86_64_kvm
hard_limit     : 1024000 kB
soft_limit     : unlimited
swap_hard_limit: 1024000 kB

(In reply to comment #9)
> (In reply to comment #8)
> > No, that's not expected. Are you sure you are running the right libvirtd
> > version? virsh memtune works as expected for me with the latest
> > libvirt-0.8.7-17.el6 package.
> 
> Hi Jiri,
> I saw 'Fixed In Version: libvirt-0.8.7-16.el6' on the right top, so I used -16
> version to verify the bug, please update 'Fixed In Version' for the bug.

It should also work with -16 and even older packages. The only thing we fixed for this BZ was documentation of memtune command and that was done in -16 so Fixed In Version is correct. Since you got an error about unsupported qemuDomainGetMemoryParameters API, an ancient libvirtd must have been running.

An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.

http://rhn.redhat.com/errata/RHBA-2011-0596.html

This still seems to be a problem in 0.8.7-18.  The memtune function does not seem supported.

# virsh memtune store_0
error: Unable to get number of memory parameters
error: this function is not supported by the connection driver: qemuDomainGetMemoryParameters


# virsh dominfo store_0
Id:             4
Name:           store_0
UUID:           2b4b0dab-4160-d396-34be-10572b478dd6
OS Type:        hvm
State:          running
CPU(s):         1
CPU time:       153.4s
Max memory:     2048000 kB
Used memory:    2048000 kB
Persistent:     yes
Autostart:      disable
Security model: selinux
Security DOI:   0
Security label: system_u:system_r:svirt_t:s0:c194,c863 (enforcing)

# uname -r
2.6.32-131.17.1.el6.x86_64

# rpm -q qemu-kvm
qemu-kvm-0.12.1.2-2.160.el6_1.8.x86_64

# rpm -q libvirt
libvirt-0.8.7-18.el6_1.1.x86_64