- Stan Hoeppner stan@hardwarefreak.com:
Does this machine have more than 4GB of RAM? You do realize that merely utilizing PAE will cause an increase in context switching, whether on bare medal or in a VM guest. It will probably actually be much higher with a VM guest running a PAE kernel. Also, please tell me the ESX kernel you're running is native 64 bit, not 32 bit. If the VMWare kernel itself is doing PAE, as well as the guest Linux kernel, this may fully explain the performance disaster you have on your hands, if it is indeed due to context switching.
It sure work with 1.2.x now, so that's not really the problem
The bigger question is, why does this problem surface so readily while running Dovecot 2.0.x and not while running Dovecot 1.2.x?
EXACTLY
Is 1.2.x merely tickling the dragon's chin, whereas 2.0.x is sticking it's head into the dragon's mouth?
I'd say the difference between 1.2 and 2.0 is so dramatic that it's probably something else.
This very well may be the case. You need to also look at the CONFIG_HZ= value of the Linux kernel of the guest. If it's a tickless kernel you should be fine. If tickless, IIRC, you should see CONFIG_NO_HZ=y.
# fgrep HZ config-2.6.32-23-generic-pae CONFIG_NO_HZ=y # CONFIG_HZ_100 is not set CONFIG_HZ_250=y # CONFIG_HZ_300 is not set # CONFIG_HZ_1000 is not set CONFIG_HZ=250 CONFIG_MACHZ_WDT=m
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