Re: FSI TX200 S2 and main memory > 4 GB

I have a strong impression, that benefits from HugeTLB-s on a small (<= 4GB)
and medium size (<= 16 GB) servers are strongly overestimated, while
problems with them (no automated memory allocation, implementation
instability and so on) are underestimated.

Can't find exact numbers, but few charts which I find show 1 - 3 % benefits
from using hugetlb in few particular cases.
My own experiments (with Oracle cluster and 4 GB servers) was not clean but
show, that it's pretty simple to broke OS or slow it down by inproper
hugetlb configuration.

So I'd better be very careful with them, and they definitely are not
mandatory required on 64 bit Linux.



> Did you enable huge pages with your 64-bit setup.  It seems to be a
> common misconception the hugepages is not important with 64-bit but this
> is not true.  Actually, it can be even more important because the entire
> SGA is allocated to Oracle directly rather than via indirect buffers.
>
> For example, if you have a 6GB SGA on 64-bit linux you should probably
> have somewhere around 3000 Hugepages allocated.
>
> Just a thought.
>
> Later,
> Tom


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