What is the memtester tool called here?

[drosophila]

The usual way of booting memtest86+ is highly disruptive, so it would be nice to have a tool like memtester that could be run during normal operation, maybe even scheduled monthly runs, since memory issues can develop over time so monitoring might be good. The plugins section doesn't provide anything of that sort/name so what am I overlooking?

[Mpegger]

... so what am I overlooking?

For the same reason a program like badblocks can't test a drive that is mounted and in use, memtest can't test RAM while it's in use by anything other then itself.

memtester will malloc(3) the amount of memory specified, if possible. If this fails, it will decrease the amount of memory requested until it succeeds. It will then attempt to mlock(3) this memory; if it cannot do so, testing will be slower and much less effective. Run memtester as root so that it can mlock the memory it tests

[connervt]

What would be the benefit of running memtest86+ if it cannot test all of the installed memory?  Only testing a portion of your memory does not give you any conclusive result.  And avoiding memory used by the system/OS is even less valuable, for this would be the area which you would really wish to know if there is an issue.