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Re: [Xen-users] How could I find memory hogging process in Dom0?


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  • From: Christopher Myers <cmyers@xxxxxxxxxxxx>
  • Date: Fri, 23 Mar 2018 14:21:38 +0000
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  • Thread-topic: [Xen-users] How could I find memory hogging process in Dom0?


Thanks for your answer, Christopher and Phil.
I also know that it is better to use the free memory as cache for file backed data or buffer rather than just leave it unused as you mentioned.

However, this is happening all the time, even if I reboot the machines.
And it causes performance degradation of B. So I need to find some way to resolve this problem.

After discovering performance degradation of B, I've reported some of the results of checking some of the two devices.
Because I installed Xen on the 2 PCs in the same way, I cannot understand why this is happening and I need to ask your help.


Out of curiosity, how much memory does your host have? Are you oversubscribing?

Also, what kind of performance degradation are you seeing on B? Are you possibly being bitten by the spectre/meltdown cpu "fixes" masquerading as other problems?

Have you done the performance tuning on your dom0 like is listed here? https://wiki.xen.org/wiki/Tuning_Xen_for_Performance

Regardless of how much memory you allocate to a linux machine, it will always use as much memory as it can. So if you gave your host 100GB of memory, it would try to find a way to use up pretty much all of it, even if that means caching a file that you used one time in memory. So every time you increase the memory on a domu, it will look like it's just sucking it up, when in reality, it's just taking advantage of the resources that you provided it.

FWIW, on my Debian Stretch Xen host at home, it has 4GB of memory total. I've allocated a fixed 512MB to dom0, 2GB to one domu, and 384MB to three other domu's, and it runs circles around my previous vmware host, even when running intensive stuff like my Minecraft server that I host for my friends and I.

Chris

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