Topic
  • 10 replies
  • Latest Post - ‏2010-09-10T20:43:05Z by pmak
rgar
rgar
3 Posts

Pinned topic vmstat, what does ENT mean?

‏2009-10-22T18:17:17Z |
System configuration: lcpu=4 mem=16384MB ent=0.50

kthr memory page faults cpu time
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------------
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r b avm fre re pi po fr sr cy in sy cs us sy id wa pc ec hr mi se

In the Documentation it says ENT is only used if running shared processors, but it doesn't say what it actually is telling you.
I know what pc and ec mean in the stats, but what is it telling me here with ent and a link to any documentation explaining it further would be appreciated.
Updated on 2010-09-10T20:43:05Z at 2010-09-10T20:43:05Z by pmak
  • donwinterhalter
    donwinterhalter
    19 Posts

    Re: vmstat, what does ENT mean?

    ‏2009-10-22T21:52:44Z  
    Are you running on an LPAR? I think it means Entitled capacity but I'm home and just guessing. Run lparstat -i to see if I'm right.
  • rgar
    rgar
    3 Posts

    Re: vmstat, what does ENT mean?

    ‏2009-10-23T14:00:07Z  
    Are you running on an LPAR? I think it means Entitled capacity but I'm home and just guessing. Run lparstat -i to see if I'm right.
    That's what I thought it was too, but I can't find any documentation supporting that to be sure. I was asked what this means on a vmstat off an outside system. They are running lpars, but we don't use lpars in house so I can't do any testing to make sure. There is no ENT in a vmstat that doesn't seem to be running lpars. I guess I'll just have to assume your answer is right.
  • donwinterhalter
    donwinterhalter
    19 Posts

    Re: vmstat, what does ENT mean?

    ‏2009-10-23T14:34:21Z  
    • rgar
    • ‏2009-10-23T14:00:07Z
    That's what I thought it was too, but I can't find any documentation supporting that to be sure. I was asked what this means on a vmstat off an outside system. They are running lpars, but we don't use lpars in house so I can't do any testing to make sure. There is no ENT in a vmstat that doesn't seem to be running lpars. I guess I'll just have to assume your answer is right.
    I haven't found much documentation for the "System configuration:" line produced by many of the common monitoring tools like vmstat and sar. I use these utilites a lot because I'm one of the developers for SarCheck, so I've been looking at them since they first started appearing a few years ago.

    Anyway, I did find some information about the "ent=" field. Please look at this document on tuning from January 2009:

    http://www-03.ibm.com/servers/enable/site/peducation/wp/162b6/162b6.pdf

    At the end of the vmstat section on PDF page 10 (labelled page 8), you'll see ent=2.00 in figure 5. The description of the "ec" column includes the fact that "ent=" means entitled capacity. And like I said last night, this can be confirmed by running lparstat -i .
  • rgar
    rgar
    3 Posts

    Re: vmstat, what does ENT mean?

    ‏2009-10-23T14:56:25Z  
    I haven't found much documentation for the "System configuration:" line produced by many of the common monitoring tools like vmstat and sar. I use these utilites a lot because I'm one of the developers for SarCheck, so I've been looking at them since they first started appearing a few years ago.

    Anyway, I did find some information about the "ent=" field. Please look at this document on tuning from January 2009:

    http://www-03.ibm.com/servers/enable/site/peducation/wp/162b6/162b6.pdf

    At the end of the vmstat section on PDF page 10 (labelled page 8), you'll see ent=2.00 in figure 5. The description of the "ec" column includes the fact that "ent=" means entitled capacity. And like I said last night, this can be confirmed by running lparstat -i .
    Thanks,
  • nagger
    nagger
    1698 Posts

    Re: vmstat, what does ENT mean?

    ‏2009-10-24T20:42:26Z  
    • rgar
    • ‏2009-10-23T14:56:25Z
    Thanks,
    You are correct ent=NNN.N in the top line is the Entitled CPU capacity of the Logical Partition (LPAR) and it is only shown if this is a Shared CPU LPAR.

    This number is the guaranteed CPU time available to the LPAR.
    If the LPAR is uncapped, you can use more than this number (if available).
    If capped then its the maximum.
    Nothing can stop the LPAR getting this much CPU time.

    I have reported this odd omission to the manual page to the developers.

    Thanks Nigel
  • nagger
    nagger
    1698 Posts

    Re: vmstat, what does ENT mean?

    ‏2009-10-24T20:42:40Z  
    • rgar
    • ‏2009-10-23T14:56:25Z
    Thanks,
    You are correct ent=NNN.N in the top line is the Entitled CPU capacity of the Logical Partition (LPAR) and it is only shown if this is a Shared CPU LPAR.

    This number is the guaranteed CPU time available to the LPAR.
    If the LPAR is uncapped, you can use more than this number (if available).
    If capped then its the maximum.
    Nothing can stop the LPAR getting this much CPU time.

    I have reported this odd omission to the manual page to the developers.

    Thanks Nigel
  • pmak
    pmak
    2 Posts

    Re: vmstat, what does ENT mean?

    ‏2010-08-30T21:13:06Z  
    • nagger
    • ‏2009-10-24T20:42:40Z
    You are correct ent=NNN.N in the top line is the Entitled CPU capacity of the Logical Partition (LPAR) and it is only shown if this is a Shared CPU LPAR.

    This number is the guaranteed CPU time available to the LPAR.
    If the LPAR is uncapped, you can use more than this number (if available).
    If capped then its the maximum.
    Nothing can stop the LPAR getting this much CPU time.

    I have reported this odd omission to the manual page to the developers.

    Thanks Nigel
    I've the following output from vmstat

    System configuration: lcpu=8 mem=28672MB ent=3.30

    What does 3.30 mean? Is that supposed to mean a fraction of 8 is entitled, or does the ".30" mean something else?

    Thanks in advance.
  • nagger
    nagger
    1698 Posts

    Re: vmstat, what does ENT mean?

    ‏2010-09-08T16:45:52Z  
    • pmak
    • ‏2010-08-30T21:13:06Z
    I've the following output from vmstat

    System configuration: lcpu=8 mem=28672MB ent=3.30

    What does 3.30 mean? Is that supposed to mean a fraction of 8 is entitled, or does the ".30" mean something else?

    Thanks in advance.
    The ent=3.30 means the LPAR is entitled (guaranteed) 3.3's worth of CPU time.
    This can be spread across the CPUs that you have - in this case lcpu=8.
    Note these are logical CPUs. So if
    SMT is off that is 8 physical CPUs,
    SMT=2 that is 4 physical CPUs,
    SMT=4 that is 2 physical CPUs (SMT=4 arrived with POWER7).

    If the LPAR is capped it will use 3.3 CPUs worth of clock cycles every 10 milliseconds and then get thrown off the CPUs until the end of the dispatch 10 msec cycle.

    If uncapped it will compete for the "spare" unused CPU cycles with other uncapped LPARs and carry on running.

    The lcpu=8 means there is a maximum number of CPU it can use i.e. all 8. It can't also run on a 9th, 10th CPU etc. because it is not aware that is a possibility.

    Hope this helps, ta Nigel
  • puvichakravarthy
    puvichakravarthy
    55 Posts

    Re: vmstat, what does ENT mean?

    ‏2010-09-09T05:29:43Z  
    • nagger
    • ‏2010-09-08T16:45:52Z
    The ent=3.30 means the LPAR is entitled (guaranteed) 3.3's worth of CPU time.
    This can be spread across the CPUs that you have - in this case lcpu=8.
    Note these are logical CPUs. So if
    SMT is off that is 8 physical CPUs,
    SMT=2 that is 4 physical CPUs,
    SMT=4 that is 2 physical CPUs (SMT=4 arrived with POWER7).

    If the LPAR is capped it will use 3.3 CPUs worth of clock cycles every 10 milliseconds and then get thrown off the CPUs until the end of the dispatch 10 msec cycle.

    If uncapped it will compete for the "spare" unused CPU cycles with other uncapped LPARs and carry on running.

    The lcpu=8 means there is a maximum number of CPU it can use i.e. all 8. It can't also run on a 9th, 10th CPU etc. because it is not aware that is a possibility.

    Hope this helps, ta Nigel
    lcpu / smt gives the number of virtual cpus and not the physical cpus. Virtual cpus are actually time slices of physical cpus. So each vcpu does not necessarily need to have a 1 to 1 mapping with physical cpus. I believe you too meant the same.

    In case of dedicated partition vcpu, physical cpu have a 1 to 1 mapping.

    Regards,

    Puvi
  • pmak
    pmak
    2 Posts

    Re: vmstat, what does ENT mean?

    ‏2010-09-10T20:43:05Z  
    • nagger
    • ‏2010-09-08T16:45:52Z
    The ent=3.30 means the LPAR is entitled (guaranteed) 3.3's worth of CPU time.
    This can be spread across the CPUs that you have - in this case lcpu=8.
    Note these are logical CPUs. So if
    SMT is off that is 8 physical CPUs,
    SMT=2 that is 4 physical CPUs,
    SMT=4 that is 2 physical CPUs (SMT=4 arrived with POWER7).

    If the LPAR is capped it will use 3.3 CPUs worth of clock cycles every 10 milliseconds and then get thrown off the CPUs until the end of the dispatch 10 msec cycle.

    If uncapped it will compete for the "spare" unused CPU cycles with other uncapped LPARs and carry on running.

    The lcpu=8 means there is a maximum number of CPU it can use i.e. all 8. It can't also run on a 9th, 10th CPU etc. because it is not aware that is a possibility.

    Hope this helps, ta Nigel
    thanks nigel and puvi