What is JIT Anyhow?

Discussion in 'Android Hacks and Help' started by nateccnn, Apr 4, 2010.

  1. nateccnn

    nateccnn Active Member

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    Been playing with roms and kernels all day today. I had Bugless Beast .9 with Adamz 250 to 1100 kernel and all was fine. Short bench tests ran close to 300. I knew I could get that lower so I flashed a copy of JIT I had downloaded weeks ago. Got the short bench test down to 192.

    Then I look into settings and find I now have BB .7!

    So I flashed Smoked Glass V6.0.1 and Admaz 250 to 900 MHZ kernel. I found another copy of JIT and flashed it. The Firmware version used to say 2.1 (ESE53) and now it just says 2.1. And the Build number changed to P3Droid has assimilated your droid. Kernel stayed the same with Adamz #4.

    Is there a different version of JIT for each of these custom roms? If so...where do I find the one that works with Adamz Smoked Glass and Adamz Kernels? This last version ac tually slowed down my Droid.

    Nate
     
  2. adrynalyne

    adrynalyne Premium Member
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    JIT is Just in Time Compiler. Java apps get compiled upon execution, and this speeds it up.

    Of course the app has to be compiled with the right options to use it, and almost no apps have been, including Android as a whole. There are some proof of concept apps and benchmark apps, but real world performance does not yet exist. This will certainly change in the future when it is no longer epxerimental and deemed stable by Google.
     
  3. jasonb

    jasonb Active Member

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    jit stands for "just-in-time. i'm not really sure what it does though.

    all i know is a couple hours ago i did the jit update.zip on my droid which is running smoked glass v6.0.1 at 1ghz and it definitely made the phone faster. on the first boot it instantly did a boot loop but has been perfectly stable since. it increased my already good short benchmarks by about 30-40ms. im getting as low as 165ms at 1ghz.
     
  4. nateccnn

    nateccnn Active Member

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    Thanks, Adrynylyne. I actually know what JIT is. That was not the right way to ask what i was asking. Sorry. What I wanted to know is...does each of the various custom ROMs (Smoked Glass, Bugless Beast, Cyanogen...yours) need it's own JIT enabler or is there one generic JIT that works with all roms without over writing the firmware version?

    Nate
     
  5. jasonb

    jasonb Active Member

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    jit is jit. it does not need to be a different version for each rom.
     
  6. adrynalyne

    adrynalyne Premium Member
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    Well, initially the hack was compiled from aosp, but now....I don't know.


    I'll leave that to people who have messed with that to answer it :)
     
  7. nateccnn

    nateccnn Active Member

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    Did it change the firmware reported in your settings--about phone?

    Nate
     
  8. jasonb

    jasonb Active Member

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    yes, but it's still the same rom. i simply went into build.prop and changed the text back to what it said before because im anal like that.

    the jit update.zip file is very tiny, there is not enough data in there to actually modify the rom. it just enables jit.
     
  9. adrynalyne

    adrynalyne Premium Member
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    Oh it definitely modifies the ROM. Its installing an entirely different VM, and a few other system files.
     
  10. jasonb

    jasonb Active Member

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    i understand that. it's not changing the whole rom though. the op was worried about how the info on the info page in the settings menu had changed.

    if you install it on top of BB v9 you'll still be on BB v9. if you install it on top of smoked glass, you'll still be on smoked glass.
     
  11. adrynalyne

    adrynalyne Premium Member
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    Oh I see.

    10 char
     
  12. nateccnn

    nateccnn Active Member

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    Yes, Adrynalyne...that is what I was thinking too. And I can't really see a difference in real time application but the short bench test in SetCPU sure goes down. I guess if I obsess myself with bench tests I should keep JIT. But I think I like the stability of SG as it was written by Adamz. I'm going to leave it off for now. I am getting 300s on the short bench test and while that is not as lowest as I have seen...it is certianly faster than stock and my 118 page catalog (word doc) opens zippy fast so I think I will just leave it as it is.

    I am tempted to try your work next. I saw where you've posted up some kernels for some others on the forum. But not today. I think I am done for now.

    Nate
     
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