JIT on Eclair

[Kaesar]

Hi All,

I've managed to get JIT from Froyo working on Eclair. It won't provide
the same kind of speed increase as Froyo would, however it does seem
to be increasing performance anywhere from 50% upto 100%, depending on
the app. I need to look more into the environment variables for it to
see if I can get any extra performance. So far the update replaces
only the main DalvikVM library, where as Froyo will have optimisations
in the other related libraries too. If I get a chance I may try to
take at look at these also, however it might require some extensive
reading as I am not that familar with it. Anyhow I have done some
benchmarks using the stock platform and then with JIT enabled.

Stock
--------
Linpack: 2.27 mflops
Benchpi: 11500ms
Benchmark - cpu: 99 score

JIT
--------
Linpack: 3.95 mflops
Benchpi: 8056ms
Benchmark - cpu: 205 score

As you can see it does seem to vary depending on the app. When I tried
the benchmarks in 'setcpu' they didn't show any improvement, so there
are scenarios where it won't increase performance at all.

I would imagine with a more optimised kernel that it will provide
further speed increases. The guys working on a custom rom for the
samsung moment (same soc/processor as us) have managed to get scores
of 9~mflops on linpack. So we should certainly be able to make our
'Jet's fly in the future.

Cheers,

Kaes

[Dopi]

Hi Kaes,

this is really great new to hear. Many people put the JetDroid project in question as they say the phone will be over aged very soon. I think your work shows that it can be at least a good medium class Android smartphone for the next two years. Many people tend to forget that the Jet was performance-wise a top end phone by the time it was released. Even today many (low to mid-end) Android phones are released that are slower than the Jet. Thus your work on the JIT VM will help keep the performance up. I hope the work on the kernel will pay off soon and we get more useful function from JetDroid.

Cheers,

Dopi

P.S.: Are you aware that the SamDroid project is working on Froyo for the i5700 (Spica). I expect we can use there system with very little modifications for the Jet. The source repo is here: http://github.com/SamdroidMod .

[Kaesar]

Hi Dopi,

I completely agree there, I'm pretty certain that at the time of
release our phone had one of the highest, if not joint highest
clockspeed. There are still a lot of new phones that are out/coming
out that will be running 2.2 like the HTC Bee which have lesser specs
like a QVGA display and a 528MHz Qualcomm processor. Also you can see
the popularity in similar hardware based android phones by looking at
communities for both the 'Galaxy Spica' and 'Moment'.
I believe the problem here is that most people want it 'done' now and
lack the patience to wait. Unfortunately, as we both know, due to the
complexity of the task that it just isn't that easy nor is it a 5
minute job. I am not well versed with either phone hardware or writing
code for hardware, however I do have a reasonable understanding of
linux, kernel compiling and also working things out. So hopefully by
getting stuff such as rooting/JIT working it will show people that
there still is interest in the project.
In terms of updates, I think the problem is a lot of users aren't
aware or don't know how to check 'commits' to the git source and
therefore because there isn't anything posted in the wiki they then
assume nothing is being done. Maybe the RSS feed for the experimental
branch could be added directly to an update page on the wiki or
something?
Yes I did see that they were working on getting Froyo on the Spica,
was thinking of giving it a try but not hopeful that it would boot
straight off and as I have done quite a few changes to my current
JetDroid platform I don't really wish to start from scratch, therefore
I might consider picking up a cheap 4gb micro sdhc for this very
reason. However if anyone does already have a non-working JetDroid
installed and they are going to wipe it they could always download the
Froyo build from the Samdroid forum and see how far it will boot.

Cheers,

Kaes