Red Hat Bugzilla – Bug 982245
vdsm is reporting negative values for available memory
Last modified: 2016-02-10 15:18:12 EST
+++ This bug was initially created as a clone of Bug #956750 +++
Description of problem:
VDSM is reporting negative values for available memory.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Run memory load on host
2. vdsClient -s 0 getVdsStats | grep memAvailable
VDSM reports negative values ( memAvailable = -818 )
VDSM should never report negative values for available memory
--- Additional comment from Doron Fediuck on 2013-06-03 08:04:09 EDT ---
--- Additional comment from Saveliev Peter on 2013-06-04 06:26:23 EDT ---
The current memory computation is accurate and takes into account memory overcommitment. That's why one can get negative values there even if there is no KSM running.
Maybe it should be mentioned in the docs — then open docs issue, please. But it is not a bug.
--- Additional comment from Oded Ramraz on 2013-06-05 05:29:29 EDT ---
Peter , can we show 0 instead of negative number?
Showing negative numbers as for available memory has bad user experience / impact.
--- Additional comment from Saveliev Peter on 2013-06-05 05:45:12 EDT ---
Technically speaking, we can show anything. Yes, we can split one value into two: available memory (from 0 to N) and memory overcommitment (from -N to -1).
But since this particular value is used only in the engine, it is better to keep current behaviour:
1. users are not supposed to do anything with VDSM ←→ engine protocol
2. the engine can rely on this values
vdsClient is written to be used by experienced administrators and developers, so it is better to mention this particular case in the project documentation, 'cause it can be confusing.
--- Additional comment from Michal Skrivanek on 2013-06-05 05:58:27 EDT ---
I second the suggestion to keep showing negative values and provide an explanation in docs.
--- Additional comment from Doron Fediuck on 2013-06-10 12:00:05 EDT ---
Re-opening on the engine as this is creating false events in the system.
Additionally, the existing logic in the system should be verified in this light.
--- Additional comment from ofri on 2013-06-23 03:45:33 EDT ---
After discussion: This bug will require both change in VDSM and engine.
VDSM currently does not report the true free memory on the host. instead it reports the total memory minus the sum of all used memory (for all processes).
VDSM should report true free mem on host. this data should be the one referenced by the engine in context of 'minimum memory' events.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.