[PLUG] help with /proc/cpuinfo
Ben Koenig
techkoenig at gmail.com
Sun Apr 28 22:25:18 UTC 2019
Forgive my ignorance in resurrecting this, but isn't the primary purpose
of a VM to partition system resources?
Is this "noisy neighbor" problem a side effect of using VM's, or just
bad VM management on the part of the host? This whole Cloud idea seems
pretty pointless if a single VM is able to consume CPU time in the same
way a normal process does. You might as well just give everyone a user
account and let them fight over a shared pool of RAM.....
Just curious to know if the path forward in a situation like this is to
blame the configuration or the technology itself. Would this be any
different on a different hypervisor...etc.
On 4/25/19 1:17 PM, VY wrote:
> Hi Aaron
>
> Thanks for confirming. I do not yet know how to troubleshoot in a Xen env
> but now that you
> dissected the data with me (which no one on our team has so far), I
> understand the situation now.
>
> There's no much I can do, and we do not have another place to migrate this
> image.
> Oh well....
>
> thanks again!
>
> -v
>
>
> On Thu, Apr 25, 2019 at 1:05 PM Aaron Burt <aaron at bavariati.org> wrote:
>
>> On 2019-04-25 10:54, VY wrote:
>>> Yes, I love to learn as well.
>>>
>>> This is the output to lscpu:
>>> Architecture: x86_64
>> [...]
>>> Hypervisor vendor: Xen
>>> Virtualization type: full
>> Ah-hah. You're in a VM, and I'll bet you have a "noisy neighbor."
>>
>>> The load average is:
>>> load average: 464.68, 415.14, 416.96
>>> which does not make sense at all.
>> Loadavg is just how many processes are waiting to use the CPU.
>>
>>> The rest of TOP:
>>> Cpu(s): 51.3%us, 16.0%sy, 0.0%ni, 32.0%id, 0.0%wa, 0.0%hi,
>>> 0.4%si,
>>> 0.2%st
>>>
>>> If I hit 1, it affects all 4 CPUs.
>> All good. Very much looks like a "noisy neighbor" problem, which is
>> when another VM on the hypervisor is hogging all the CPU (or RAM) and
>> leaving you with no compute resources. From your VM's perspective, it's
>> going at the rated clock speed, but time is going by REALLY FAST.
>>
>>> Can you elaborate on why
>>> > apicid : 25
>>>> initial apicid : 25
>>> 25 is a weird number? From an earlier thread, is this simply a
>>> logical
>>> ID?
>> Eh, sort of. There should only be a couple APICs in the system. And
>> usually it'll be pretty consistent.
>> But since it's a VM all bets are off.
>>
>>> All the other systems are reporting this number as 4 and all of them
>>> are
>>> having reasonable load.
>> They're on a different hypervisor machine, and probably a different
>> version of the hypervisor software.
>>
>>> I do not have root access nor sudo. I want to try and find out why
>>> the load is so high before I escalate and argue for more privilege.
>>> When I brought this up to the responsible team, I was given a probable
>>> cause -- There are other activities hosting this VM server and they are
>>> causing this issue.
>> So they already told you that you have a noisy neighbor. All right
>> then. Don't use that VM and get by on the 3 you have, or ask the team
>> to migrate your slow VM to a different hypervisor machine, or ask for a
>> new VM on a less loaded hypervisor machine. But unless the noisy
>> neighbor calms down it sounds like your one sad VM isn't getting any
>> better.
>>
>> Is this a customer-facing service? If so, you should point this out to
>> your hosting team.
>>
>> Good luck,
>> Aaron
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