Hi group,
i tried to narrow down the problem.
Using the perf top tool i examined the processes while running.
On RHEL 7 (VAST 8.5.2):
i saw that the smalltalk process seems to be using a lot of time in two points called L226 and L679 (about 24% and 18%).
The third place is mergeRelocationFunction at about 5%.
(These symbols can be looked up with nm, they exist in esvmnx40.so.)
On RHEL 6 (VAST 8.5.2):
no single point seems to exceed 5%, and i see a lot of different function names in the topmost places of perf
(VMprMBAGetInstVarWP, methodNativeExecuteNextBytecode, nativeExecuteNextBytecode VMprPointersWithoutAt, sendSpecial, etc.).
L226 and L679 also occur but only with values below 1%.
I have the feeling, that here the VM seems actually doing things.
On RHEL 7 (VAST 9.1.0):
Again similar behaviour as with VAST 8.5.2, the names are different EsGGC 38%, markAndLinkAll 31%, mergeRelocationFunction 5%.
It seems on RHEL 7 that VAST is very busy doing some garbage collection instead of "real" work.
Is it possible that the os libraries have changed so much, that the way of allocating/disallocating memory is now extremely inefficient?
(Just guessing.)
My colleague suggested that it possibly could be the result of some kernel patch (such as meltdown).
Any other suggestions?
Regards,
Hermann Ottens