Jazelle worked for its target market (or at least, I've never seen anyone claim otherwise).
But its target market wasn't "faster java". Instead Jazelle promised better performance than an interpreter, with lower power draw than an interpreter, but without the memory footprint and complexity of a JIT. It was never meant to be faster than a JIT.
Jazelle made a lot of sense in the early 2000s where dumb phones where running J2ME applets on devices with only 1-4MB of memory, but we quickly moved onto smartphones with 64MB+ of memory, and it just made more sense to use a proper JIT.
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JavaStation might as well been vaporware. Sure, the product line existed, but the promised "Super JavaStation" with a "java coprocessor" never arrived, so you were really just paying sun for a standard computer with Java pre-installed.
I briefly worked in a team that implemented a JVM on a mobile OS (before the iPhone) and one of the senior devs said Jazelle was in effect very inefficient because of all the context switching between ARM mode and Jazelle mode.
Turned out a carefully tuned ARM JVM was in practice th best
The JavaStation is what led me to this. They sucked, Java OS sucked, and the whole idea was DOA precisely because they didn't do something like this and instead decided to make a shitty sparc machine for the 5 people that wanted a Java branded thin client
I never understood why AOT never took off for Java. The write once run anywhere quickly faded as an argument, the number of platforms that a software package needs to support is rather small.
We did see a recent attempt to do hardware-based memory management again with Vypercore, but they ran out of money.
I think part of the problem with any performance-related microarchitectural innovation is that unless you are one of the big players (i.e. Qualcomm, Apple, Intel, AMD, Nvidia) then you already have a significant performance disadvantage just due to access to process nodes and design manpower. So unless you have an absolutely insane performance trick, it's still not going to make sense to buy your chip.
They have the volume as well, if you do carve out a niche they’ll just add it and roll over you.
That’s held for decades though I think it only really worked when computers where doubling in speed every 12-18 months, for a while they scaled horizontally (more cores) over radical IPC improvements so we might see the rise of proper co-processors again (but nothing stops the successful ones getting put on die, like Strix Point is already heading).
phire|3 months ago
But its target market wasn't "faster java". Instead Jazelle promised better performance than an interpreter, with lower power draw than an interpreter, but without the memory footprint and complexity of a JIT. It was never meant to be faster than a JIT.
Jazelle made a lot of sense in the early 2000s where dumb phones where running J2ME applets on devices with only 1-4MB of memory, but we quickly moved onto smartphones with 64MB+ of memory, and it just made more sense to use a proper JIT.
---------
JavaStation might as well been vaporware. Sure, the product line existed, but the promised "Super JavaStation" with a "java coprocessor" never arrived, so you were really just paying sun for a standard computer with Java pre-installed.
markb139|3 months ago
mghackerlady|3 months ago
dehrmann|3 months ago
ck45|3 months ago
IshKebab|3 months ago
We did see a recent attempt to do hardware-based memory management again with Vypercore, but they ran out of money.
I think part of the problem with any performance-related microarchitectural innovation is that unless you are one of the big players (i.e. Qualcomm, Apple, Intel, AMD, Nvidia) then you already have a significant performance disadvantage just due to access to process nodes and design manpower. So unless you have an absolutely insane performance trick, it's still not going to make sense to buy your chip.
noir_lord|3 months ago
That’s held for decades though I think it only really worked when computers where doubling in speed every 12-18 months, for a while they scaled horizontally (more cores) over radical IPC improvements so we might see the rise of proper co-processors again (but nothing stops the successful ones getting put on die, like Strix Point is already heading).