User report: Memory usage is almost always > 90% on Linux, investigate why about applicationinsights-profiler-aspnetcore HOT 9 CLOSED

Adding to Saar's point, the calculation is correct but expected in Linux if we don't include the available memory, customers will not benefit from this trigger with this current state unless this trigger measures against the host node and not the container. If the Host level is not feasible, below are the results of my testing and proposed calculation:

From the container:

As you can see, the free memory is 81/1790 of Total memory, so the number is 95%. we can see that the container is idle because:
1- High amount of allocated memory for buff/cache (expected)
2- Swap memory is not being used, more details in the below image, there is no high si/so operations:

In my testing if we can make the calculation 1 - (Free + Available)/Total, it will be close to the actual host memory usage:

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@mumustafa, thanks for chiming in. I am considering a simpler calculation of:
1 - available / total

Here are my reasons:

1. According to the spec:

             MemAvailable %lu (since Linux 3.14)
                    An estimate of how much memory is available for
                    starting new applications, without swapping.
   

   And that's what the user actually cares about - how much memory is available.

2. It's more accurate, and I believe available already has free considered in it.

   • In a system that is heavily buffered, using your example, there's not too much difference:
     1 - (free + available) / total = 1 - (81 + 532) / 1790 = 66%, compare to:
     1 - available / total = 1 - 532 / 1790 = 70%

   • However, in a system that is not heavily buffered, like this one on a WSL:
     
     1 - (free + available) / total = 1 - (11906 + 14246) / 15930 = -64% <---- this negative number doesn't make sense. And compare to:
     1 - available / total = 1 - 14246 / 15930 = 11%

The big difference I see, is that available + free might exceed total while available is always less than the total.

Any inputs?

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@xiaomi7732 You're 100% on point, I was looking at it from the free command perspective as well: https://man7.org/linux/man-pages/man1/free.1.html

Looking at the commit description: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=34e431b0ae398fc54ea69ff85ec700722c9da773 also confirms your findings.

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Stable package released:
https://www.nuget.org/packages/Microsoft.ApplicationInsights.Profiler.AspNetCore/2.5.3

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And here's the proof of it:

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Check this out:
https://www.nuget.org/packages/Microsoft.ApplicationInsights.Profiler.AspNetCore/2.5.3-beta1

As we discussed, memory usage on linux will be computed by 1 - ( available / total ).

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Thank you Saar! this is looking great!

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Thank you for bringing this up!

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