Where are the 128-bit processors?

[Nightness]

What the topic says, 'Where are the higher bit processors?' Went from 4 to 8 to 16 to 32 to 64... Where does 128 bit stand in development atm? 

[WereCatf]

Just now, Nightness said:

What the topic says, "Where are the higher bit processors?" Went from 4 to 8 to 16 to 32 to 64... Where does 128 bit stand in development atm? 

What would be gained from moving to 128-bit CPUs? All the stuff that can actually benefit from a large number of bits already have support for such, like e.g. AVX already goes up to 512 bits.

[Gegger]

iirc there aren't 128 bit cpus right now because 64 is enough for current use

[Nightness]

Just now, WereCatf said:

What would be gained from moving to 128-bit CPUs? All the stuff that can actually benefit from a large number of bits already have support for such, like e.g. AVX already goes up to 512 bits.

Speed, like every time before when bits doubled.

[WereCatf]

1 minute ago, Nightness said:

Speed, like every time before when bits doubled.

Nope.  Doesn't work like that.

 

The biggest improvements moving from 32-bit to 64-bit came from the increased address-space and from more CPU-registers being available for use. Alas, 64-bit CPUs can address more space than we can shake a stick at, so moving to 128-bit CPUs wouldn't provide an improvement there and you can increase the number of registers available even without moving to a 128-bit CPU. Besides, increasing the number of registers will only help in cases where the current number is a bottleneck, so even that wouldn't help in everything. Also, like I mentioned, SIMD-instructions can already take advantage of up to 512 bits.

[APasz]

Know at least one was designed back in the 90's or early 00's. Don't think it was ever put in silicon.

 

Generally speaking the only reason you'd need a physical 128bit system is, if you're processing numbers above 9,223,372,036,854,775,807 often enough that the conversion to 64bit is detrimental.

There is no inherent speed bonus, in fact in theory there is a performance penalty.

[dfsdfgfkjsefoiqzemnd]

RAM is the deciding factor here.

 

16 bit systems had a RAM limit of 16MB.  Once PCs started hitting that limit, we moved to 32 bit.

32 bit systems had a RAM limit of 4GB.  We started regularly hitting that back in the '00s, which is why we moved to 64 bit.

64 bit systems can theoretically* handle up to 17 Billion GB of RAM.  Once we hit that, we'll probably move to 128 bit.

 

*  While they can indeed theoretically handle it if they were to use all 64 bits for memory, most CPUs only use 40 to 52 bits, limiting them from 1TB to 4PB of RAM.  Still, the average desktop PC is very unlikely to hit that in the next decade.