Public bug reported: libvirt < 4.3.0 had an issue whereby assigning more than 4 GB of huge pages would result in an incorrect value for the number of 4k (small) pages. This was tracked and fixed via rhbz#1569678 and the fixes appear to have been backported to the libvirt versions for RHEL 7.4+. However, this is still an issue with the versions of libvirt available on Ubuntu 16.04, 18.04 and who knows what else. We should either alert the user that the bug exists or, better again, work around the issue using the rest of the (correct) values for different page sizes.
# Incorrect value (Ubuntu 16.04, libvirt 4.0.0) $ virsh capabilities | xmllint --xpath /capabilities/host/topology/cells/cell[1] - <cell id="0"> <memory unit="KiB">16298528</memory> <pages unit="KiB" size="4">3075208</pages> <pages unit="KiB" size="2048">4000</pages> <pages unit="KiB" size="1048576">0</pages> ... </cell> (3075208 * 4) + (4000 * 2048) != 16298528 # Correct values (Fedora ??, libvirt 4.10) $ virsh capabilities | xmllint --xpath /capabilities/host/topology/cells/cell[1] - <cell id='0'> <memory unit='KiB'>32359908</memory> <pages unit='KiB' size='4'>8038777</pages> <pages unit='KiB' size='2048'>100</pages> <pages unit='KiB' size='1048576'>0</pages> ... </cell> (8038777 * 4) + (100 * 2048) == 32359908 [1] https://bugzilla.redhat.com/show_bug.cgi?id=1569678 ** Affects: nova Importance: Undecided Status: New -- You received this bug notification because you are a member of Yahoo! Engineering Team, which is subscribed to OpenStack Compute (nova). https://bugs.launchpad.net/bugs/1811870 Title: libvirt reporting incorrect value of 4k (small) pages Status in OpenStack Compute (nova): New Bug description: libvirt < 4.3.0 had an issue whereby assigning more than 4 GB of huge pages would result in an incorrect value for the number of 4k (small) pages. This was tracked and fixed via rhbz#1569678 and the fixes appear to have been backported to the libvirt versions for RHEL 7.4+. However, this is still an issue with the versions of libvirt available on Ubuntu 16.04, 18.04 and who knows what else. We should either alert the user that the bug exists or, better again, work around the issue using the rest of the (correct) values for different page sizes. # Incorrect value (Ubuntu 16.04, libvirt 4.0.0) $ virsh capabilities | xmllint --xpath /capabilities/host/topology/cells/cell[1] - <cell id="0"> <memory unit="KiB">16298528</memory> <pages unit="KiB" size="4">3075208</pages> <pages unit="KiB" size="2048">4000</pages> <pages unit="KiB" size="1048576">0</pages> ... </cell> (3075208 * 4) + (4000 * 2048) != 16298528 # Correct values (Fedora ??, libvirt 4.10) $ virsh capabilities | xmllint --xpath /capabilities/host/topology/cells/cell[1] - <cell id='0'> <memory unit='KiB'>32359908</memory> <pages unit='KiB' size='4'>8038777</pages> <pages unit='KiB' size='2048'>100</pages> <pages unit='KiB' size='1048576'>0</pages> ... </cell> (8038777 * 4) + (100 * 2048) == 32359908 [1] https://bugzilla.redhat.com/show_bug.cgi?id=1569678 To manage notifications about this bug go to: https://bugs.launchpad.net/nova/+bug/1811870/+subscriptions -- Mailing list: https://launchpad.net/~yahoo-eng-team Post to : [email protected] Unsubscribe : https://launchpad.net/~yahoo-eng-team More help : https://help.launchpad.net/ListHelp
