Hello Context : oVirt Engine Version: 3.3.0-4.el6 Hypervisor VDSM : vdsm.x86_64 - 4.12.1-2.el6 A vm : - Memory Size : 1024 Mo - Physical Memory Guaranteed : 128 Mo ;) - Memory balloon device enabled the vm is running with nearly no activity to have a constant memory used Testcase 1 : Initial run No change to the balloon Total Memory = Balloon 1024 Mo Data from vdsClient getVmStats balloonInfo = {'balloon_max': '1048576', 'balloon_min': '131072', 'balloon_target': '1048576', 'balloon_cur': '1048576'} memoryStats = {'swap_out': '0', 'majflt': '0', 'mem_free': '920308', 'swap_in': '0', 'pageflt': '7', 'mem_total': '1020576', 'mem_unused': '863500'} Here : mem_total - mem_unused = 157076 correct Data get from api (REST or Python : statistics.'memory.used') Memory used 128849018.0 = 123 Mo -------------------------------------------------------------- If i modify the balloon by the command vdsClient setBalloonTarget 524288 (512*1024) i got vds balloonInfo = {'balloon_max': '1048576', 'balloon_min': '131072', 'balloon_target': '524288', 'balloon_cur': '524288'} memoryStats = {'swap_out': '0', 'majflt': '0', 'mem_free': '396044', 'swap_in': '0', 'pageflt': '7', 'mem_total': '496288', 'mem_unused': '339228'} mem_total - mem_unused = 157076 correct value API.statistics Memory used = 665719930.0 = 635 Mo ==> (512+123) -------------------------------------------------------------- Setting a balloon to 262144 (256*1024) balloonInfo = {'balloon_max': '1048576', 'balloon_min': '131072', 'balloon_target': '262144', 'balloon_cur': '262144'} memoryStats = {'swap_out': '0', 'majflt': '0', 'mem_free': '133916', 'swap_in': '0', 'pageflt': '6', 'mem_total': '234144', 'mem_unused': '76224'} mem_total - mem_unused = correct value API.statistics: Memory used = 934155386.0 = 891 Mo (768+123) To get the correct value from the api i need to fdo [ (Memory Used/1024)- (Balloon Max - Balloon Current) ] / 1024 ------------- Of course display in manager is also wrong No Balloon parameter modified http://screencast.com/t/rGhKJgeB2ol Balloon 512 http://screencast.com/t/L7geTfnI Balloon 256 http://screencast.com/t/8jBllKXtGt7 Should we consider this as a bug ? Do you plan to change the formula to compupte the memory used ? Regards Hervé Leclerc CTO Alter Way 1, rue royale 9 ème étage 92210 St Cloud +33 1 78152407 +33 6 83979598 <http://www.alterway.fr/signatures/url/1>