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Attempting to optimize my (Main Windowless) Ubuntu system for my uses
I will detail questions below, I understand this might be the wrong place to ask these questions. If so, my apologies and I thank you so much for your patience.
Thanks to all the volenteers that have helped me learn ubuntu over the years (Since 5.10)
This is a "short" list of questions I have been trying to figure out for some time.

If you feel you can answer one but not another, that's already more than I could ask for.

I have wrote this up in a format for easy navigation to important points
Hopefully to less annoy your eyes.
You're welcome :)
or i'm sorry i annoy you. :(

If you would be so kind, Please format answers as follows:
question 1: _ _ _ _ _
or
question 1-a: _ _ _ _ _
If you want to simply link me to relevant information, rather than type up something really detailed; that would be more than awesome!

Memory Specific Questions


  • Goal: Maximizing memory bandwith to better perform in Virtualization, and Large file compression. (Possible conflict?)

    1. Ganged vs Unganged "which is better?"** is relative, i know. But what about ganged vs unganged -> With or without Bank/channel interleaving?

      • a: Speculation -> If i understand correctly, "channel interleaving has something to do with using both channels to read or write in a kind of "striping" pattern, as opposed to a standard half duplex operation.(probably wrong) but wouldn't ganged channels make this irrelevant?
    2. Memory Interleaving(bank). Does it have a down side? Does it require a ratio of clocks? (If I run 4x4gig ddr3)

      • a. If im reading correctly(trying to learn), this is designed to spread operations between latency cycles to work around the higher latency of "normal" operation.
      • b. However it seems to me that it has to be: divisible by fractions of a master clock? So if i run memory at 1333mhz, then the mean between 2 (physical) banks would operate every (roughly) 600Mhz?
      • Warning! Possibly utter nonsense: (1333/2 interleaving to act like 1 memory module per 2 sticks of a total of 4 sticks, meaning 2x channels@4)
      • c. which makes me wonder if there would be left over clock cycles the system would have to... "truncate/balance" or something? But I'm certain theres a feature somewhere i don't understand.

Virtualization Questions

  1. AMD-V -> Option of IOMMU Turned it on, why do i have extra option of "64MB"? If IOMMU is on, but "64MB" is "disabled", Is it on? (have scoured google, I still dont know)
    • a. I think i understand that its supposed to (kind of) "set aside" a part of ram to act as a faster interactive zone for "stuff" (usb, Graphics, and... what?)
    • b. I am using Nvidia graphics on AMD (Used kernel option "iommu=pt iommu=1, pt "passthrough"? No idea what they do, found it on google to solve boot up issue)
    • c. Will this option help me use low latency sound hardware, like my midi keyboard?
  2. Can you recommend any additional tweaks?
    • a. sysctl settings?
    • b. swap settings?

Grats, youve reached the end.
Thanks for Reading.

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closed as not constructive by Bruno Pereira Jun 15 '12 at 15:19

As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, visit the help center for guidance.If this question can be reworded to fit the rules in the help center, please edit the question.

2  
One question per question, please! See the FAQ. –  izx Jun 15 '12 at 15:06

1 Answer 1

Memory, in general:

More is better, even if "slower". Reasoning: memory is SO MUCH FASTER than ANYTHING else that even an extra 512Mb is significantly better than even an added 4Gb of SSD cache (if it were possible to implement such a thing). Super-fast vs "just fast" is useless if what you're looking for isn't in the ram to begin with (because one way or another it had to be evicted for space).

Regarding swap:

For a virtual machine (assumption on my part), swap/virtual memory isn't a horrible idea if mapped directly to disk space, not a file on a filesystem. More removed than that, and you're going to lose efficiency, and that may "save" the system in case of "running out of memory" in the VM, but the hazards seem to outweigh the benefits.

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Ok downvoter. If I'm incorrect, then you need to put out an answer or comment that explains to me how/where my knowledge is mistaken. Otherwise, I'm going to treat your downvote as symptomatic of the Ubuntu Stack Exchange, and I'll just choose to never contribute to it again. –  killermist Jun 15 '12 at 15:22

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