Author Topic: What's happening in the world of MIPS?  (Read 2478 times)

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Online nctnico

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Re: What's happening in the world of MIPS?
« Reply #25 on: October 14, 2018, 10:59:01 pm »
I think MIPS has had happening what I am afraid will happen to ARM after the Softbank acquisition.   Probably some high management guru decided "enough with all this diversification, trying to be everything for everyone.   Focus exclusively on THIS "highly profitable" market segment (I think it was network appliances for MIPS.  It'd probably be phones for ARM.)  :-(It may sound good on paper, but it tends not to be what ends up providing innovation in CPU technology.
When ARM were developing the M3 and M0, MIPS was trying hard to go head to head with them, as they knew they could only survive by broadening their appeal across the whole of the embedded space. A number of MCU vendors evaluated the MIPS small core options, and found they had some pretty good qualities. In the end only Microchip signed up.
This probably also had to do with the large ecosystem ARM already had created. Long (20 years ago) before ARM cores turned up in microcontrollers there was already a lot of support for the ARM based SoCs. Years ago I had to work with a MIPS based SoC. It was like being in friggin no-one's land. Every piece of software had ARM optimisations but nothing for MIPS. IMHO MIPS has missed the boat. If Broadcom and Microchip stop using MIPS then it is probably game over.
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Online coppice

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Re: What's happening in the world of MIPS?
« Reply #26 on: October 14, 2018, 11:05:31 pm »
I think MIPS has had happening what I am afraid will happen to ARM after the Softbank acquisition.   Probably some high management guru decided "enough with all this diversification, trying to be everything for everyone.   Focus exclusively on THIS "highly profitable" market segment (I think it was network appliances for MIPS.  It'd probably be phones for ARM.)  :-(It may sound good on paper, but it tends not to be what ends up providing innovation in CPU technology.
When ARM were developing the M3 and M0, MIPS was trying hard to go head to head with them, as they knew they could only survive by broadening their appeal across the whole of the embedded space. A number of MCU vendors evaluated the MIPS small core options, and found they had some pretty good qualities. In the end only Microchip signed up.
This probably also had to do with the large ecosystem ARM already had created. Long (20 years ago) before ARM cores turned up in microcontrollers there was already a lot of support for the ARM based SoCs. Years ago I had to work with a MIPS based SoC. It was like being in friggin no-one's land. Every piece of software had ARM optimisations but nothing for MIPS. IMHO MIPS has missed the boat. If Broadcom and Microchip stop using MIPS then it is probably game over.
Perhaps more relevant to MCUs is the old ARM7TDMI. It only got into a few (mostly really lousy) MCUs near the end of its life, but from the mid 90s it was doing a LOT of MCU like jobs embedded in larger parts, like hard disc controllers, GSM chips, and automotive parts.
 

Offline brucehoult

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Re: What's happening in the world of MIPS?
« Reply #27 on: October 14, 2018, 11:22:55 pm »
Perhaps more relevant to MCUs is the old ARM7TDMI. It only got into a few (mostly really lousy) MCUs near the end of its life, but from the mid 90s it was doing a LOT of MCU like jobs embedded in larger parts, like hard disc controllers, GSM chips, and automotive parts.

In 2006-2008 I was working for a company selling a Java compiler for mobile phones. At least 90% were using the ARM7TDMI then.
 

Offline technix

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Re: What's happening in the world of MIPS?
« Reply #28 on: October 14, 2018, 11:45:37 pm »
I think MIPS has had happening what I am afraid will happen to ARM after the Softbank acquisition.   Probably some high management guru decided "enough with all this diversification, trying to be everything for everyone.   Focus exclusively on THIS "highly profitable" market segment (I think it was network appliances for MIPS.  It'd probably be phones for ARM.)  :-(It may sound good on paper, but it tends not to be what ends up providing innovation in CPU technology.
When ARM were developing the M3 and M0, MIPS was trying hard to go head to head with them, as they knew they could only survive by broadening their appeal across the whole of the embedded space. A number of MCU vendors evaluated the MIPS small core options, and found they had some pretty good qualities. In the end only Microchip signed up.
This probably also had to do with the large ecosystem ARM already had created. Long (20 years ago) before ARM cores turned up in microcontrollers there was already a lot of support for the ARM based SoCs. Years ago I had to work with a MIPS based SoC. It was like being in friggin no-one's land. Every piece of software had ARM optimisations but nothing for MIPS. IMHO MIPS has missed the boat. If Broadcom and Microchip stop using MIPS then it is probably game over.
Perhaps more relevant to MCUs is the old ARM7TDMI. It only got into a few (mostly really lousy) MCUs near the end of its life, but from the mid 90s it was doing a LOT of MCU like jobs embedded in larger parts, like hard disc controllers, GSM chips, and automotive parts.
And, y'know, Game Boy Advance. It is the ARM7TDMI that gave it SNES-level game experience without touching the helper chips like SuperFX and being power restricted by the handheld form factor. Nintendo stayed with ARM ever since on handhelds, even recently axed the PowerPC-based home consoles and merged it with the handhelds in the ARM-based Nintendo Switch hybrid console.

I wonder if Nintendo is one of the driving forces behind Japan-based SoftBank buying out ARM...
« Last Edit: October 14, 2018, 11:49:50 pm by technix »
 

Offline Marco

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Re: What's happening in the world of MIPS?
« Reply #29 on: October 15, 2018, 02:01:37 am »
Aren't most DSP loops controlled by a counter (e.g. array size) not by the data?

For most non-DSP architectures the difference is academic, they have no loop instructions, they can only branch on data comparisons. They don't know the data is a counter, so they can't anticipate what the comparison will be, they have to predict it and get it wrong once every loop. The x86 loop instruction is translated to branching too, so that doesn't help.

Zero overhead looping was one of the common distinguishing features of DSPs.

PS. there are ways to avoid it without loop instructions, prepare to branch instructions and manual BTB loading for instance ... but those are rare in modern architectures.
« Last Edit: October 15, 2018, 02:18:07 am by Marco »
 

Online legacy

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Re: What's happening in the world of MIPS?
« Reply #30 on: October 15, 2018, 02:08:35 am »
I wonder if Nintendo is one of the driving forces behind Japan-based SoftBank buying out ARM...

probably, but ... Japan is weird since they are also supporting SuperHitachi chip which they like to use their GPS, and it's not clear why they like to do so, but they do :-//
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Online legacy

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Re: What's happening in the world of MIPS?
« Reply #31 on: October 15, 2018, 02:13:46 am »
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Offline Marco

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Re: What's happening in the world of MIPS?
« Reply #32 on: October 15, 2018, 02:19:09 am »
It is better to know than to predict, with branch prediction you often know ... but have no way to tell the processor. You just have to sit there seeing it waste cycles.
 

Online legacy

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Re: What's happening in the world of MIPS?
« Reply #33 on: October 15, 2018, 03:03:15 am »
well, dealing with Branches in the processor pipeline has been solved by several branch prediction techniques, from Static Branch Prediction (the cheapest) to Dynamic Branch Prediction.

in every conditional branch Instruction, the branch is taken only if the condition is satisfied, and the branch target address is stored in the Program Counter (PC) instead of the address of the next instruction in the sequential instruction stream.

The branch that is guessed to be the most likely is then fetched and speculatively executed. If it is later detected that the guess was wrong then the speculatively executed or partially executed instructions are discarded and the pipeline is flushed and it starts over with the correct branch, incurring a delay.

In short, the smarter the branch prediction goes the fewer penalties are in computation being.

Therefore the point is: enhancing the prediction is a good point, and within the class of Dynamic Branch Prediction we are able, in theory, to collect a deep history of instructions and conditions running in the CPU in order to apply advanced statistics and even AI algorithms to predict branches with a low failure rate, it's called hyperdynamic branch prediction, which sounds exciting (so they said in Intel, "hyper" comes from the need of using a hyperplane, a matrix with 3 dimensions, to keep the information) except this introduces more complexity in the design of the chip, it potentially slows down the CPU ( it doesn't scale well on frequency) and more area needs to be taken in the silicon.


So ... we all prefer the KIS approach, and we have resolved the problem with the compromise of accepting a smaller pipeline. The smaller the pipeline goes (which means fewer stages) the shorter the delay of penalty goes on wrong branch predictions.


oh, reintroducing instructions like "do loop until this counter is greater than zero" would be great, but ... again it costs more complexity in RISC design.

umm, to be honest, not so much, and "Arm" stands for [A]dvanced [R]ISC [M]achine therefore if it wishes it can copy this feature from whatever implementations we have seen in CISC CPUs, even take the challenge of implementing the hyperdynamic branch prediction that will turn a CPU into a Skynet AI-driven chip(1), but ... for sure it's not compliant to the pure and minimalistic approach of MIPS processors  :D


(1) kidding. The chip mentioned in Terminator movies.
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Offline brucehoult

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Re: What's happening in the world of MIPS?
« Reply #34 on: October 15, 2018, 03:30:54 am »
Aren't most DSP loops controlled by a counter (e.g. array size) not by the data?

For most non-DSP architectures the difference is academic, they have no loop instructions, they can only branch on data comparisons. They don't know the data is a counter, so they can't anticipate what the comparison will be, they have to predict it and get it wrong once every loop.

No, that's not correct.

Modern branch prediction techniques -- which started with the Pentium MMX and Pentium Pro in the mid 90s and are now incorporated into even mid-range microcontrollers -- are capable of executing loops with trip counts of up to maybe 20 or so with *zero* mispredictions after the first couple of times.
 

Online NorthGuy

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Re: What's happening in the world of MIPS?
« Reply #35 on: October 15, 2018, 03:40:03 am »
For most non-DSP architectures the difference is academic, they have no loop instructions, they can only branch on data comparisons. They don't know the data is a counter, so they can't anticipate what the comparison will be, they have to predict it and get it wrong once every loop. The x86 loop instruction is translated to branching too, so that doesn't help.

Even naïve branch prediction (e.g. take it if it jumps back and don't take it if it jumps forward) works reasonably well and won't create much overhead on tight fast loops.

However, all these heuristic methods (caching, re-ordering, branch prediction) are good when you want to optimize average speed, but at the same time, they make the worst case worse.
 

Online legacy

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Re: What's happening in the world of MIPS?
« Reply #36 on: October 15, 2018, 03:46:33 am »
Do you know? we have reached a level of artificial intelligence in our algorithms able to predict people's purchase wishes before people actually decide to do any purchase.

These algorithms are used by Amazon, eBay, and many others for many other applications which need to predict something by identifying common patterns.

I have recently done some personal researching by applying these algorithms to my softcore with the specific purpose of reducing the failure rate at branch predicting and it has actually made by several orders of magnitude, which is extremely good! Unfortunately, the downside is that these algorithms need to learn, they need time for this, and they consume a lot of memory.

My softcore runs as a software HDL simulation, while the branch prediction unit is an external module written in C and able to interact with the HDL simulator , and every plan for a hardware translation of its algorithms has always come into the need of more ram than the FPGA can provide(1), and no less than 90 cycles to speculate on the branch prediction.

Which is definitely too crazy even for a hobby, it slows down the clock by two orders of magnitude (1:100), therefore it has been abandoned, but it has been a crazy cool show  :D


(1) more than 8Kbyte of BRAM on my little Spartan3 considering a prediction matrix to speculate on  2Kbyte of instructions.

I would infer two points on a hypothetical corollary
1) these algorithms can only be applied to small RAMs, like an L1 cache
2) judging by my implementation, 1Mbyte of L1 cache needs 4Mbyte of space for the matrix

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Online legacy

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Re: What's happening in the world of MIPS?
« Reply #37 on: October 15, 2018, 03:50:00 am »
with *zero* mispredictions after the first couple of times.

yup, These algorithms are on made on second order statistic, and they work well for loops.

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Online NorthGuy

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Re: What's happening in the world of MIPS?
« Reply #38 on: October 15, 2018, 03:59:45 am »
Do you know? we have reached a level of artificial intelligence in our algorithms able to predict people's purchase wishes before people actually decide to do any purchase.

Marketing doesn't work by predicting purchaser's wishes. It works by controlling purchaser's wishes, which is much more efficient approach.
 

Online legacy

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Re: What's happening in the world of MIPS?
« Reply #39 on: October 15, 2018, 04:59:57 am »
Marketing doesn't work by predicting purchaser's wishes. It works by controlling purchaser's wishes, which is much more efficient approach.

no doubt they make us more prone to purchase by well-done advertisements, but this is psychology matter, while computer science it's more interested in predicting algorithms based on statistics. They used these algorithms to increase the efficiency of warehouses in the first place. These algorithms are also used by the police, e.g. the "big brother" project used in the UK.

there was a crazy and funny fact happens when an artificial-intelligence-driven data analyzer predicted a sixteen years old girl was pregnant by suggesting her several purchases for a baby before her consciousness was aware of what was happening.

Oh, you could even think the data analyzer was pushing the young girl to be pregnant, but this for me sounds more "mind control" than how it should be. Why? it's just software, without any human intervention, and it keeps analyzing where you click, and for what  :-//
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Online SiliconWizard

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Re: What's happening in the world of MIPS?
« Reply #40 on: October 15, 2018, 07:56:42 am »
Quote
I believe this has been discussed several times in other threads, so you may want to do a little searching in the forum which will avoid people repeating themselves endlessly. ;D

Hey, are you trying to tell me you prefer RETs over JMP loops? 

I'll have a hunt :)

I was suspecting we'd get to read it all over again, the quirks of the dated MIPS architecture, how it's more of an academic learning tool than a practical one, how ARM has been eating MIPS alive, and a pinch of RISC-V. And finally how MIPS is dead without being really dead. Turns out that's pretty much what we got. ;D

The acquisition of MIPS by "Wave Computing" may not bode too well for the future of MIPS. AI and deep learning is all the rage, but this is just some kind of start-up as far as I got it, and this kind of acquisitions often have a bad ending.

Quoting them:
Quote
Wave is a venture capital backed startup. We will never have all the resources, as many people or as much time as we want to bring new creative solutions to the market. To be successful, we must continue to rely on innovation, the speed of action, and working hard to get our job done.

Ahem.
 

Offline brucehoult

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Re: What's happening in the world of MIPS?
« Reply #41 on: October 15, 2018, 11:08:30 am »
Do you know? we have reached a level of artificial intelligence in our algorithms able to predict people's purchase wishes before people actually decide to do any purchase.

Marketing doesn't work by predicting purchaser's wishes. It works by controlling purchaser's wishes, which is much more efficient approach.

Mostly I find that I see ads on every site I visit for a product or service I need once or once a year AND BOUGHT YESTERDAY.

Right now, I'm seeing ads everywhere from booking.com for a hotel in Fiji that I already booked on expedia on Saturday. I had checked the price on booking.com as well, just in case it was better.
 

Online NorthGuy

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Re: What's happening in the world of MIPS?
« Reply #42 on: October 15, 2018, 01:10:19 pm »
Marketing doesn't work by predicting purchaser's wishes. It works by controlling purchaser's wishes, which is much more efficient approach.

Mostly I find that I see ads on every site I visit for a product or service I need once or once a year AND BOUGHT YESTERDAY.

Right now, I'm seeing ads everywhere from booking.com for a hotel in Fiji that I already booked on expedia on Saturday. I had checked the price on booking.com as well, just in case it was better.

This is an example of good marketing. You didn't have any desire on checking prices for what you already have. Google showed you the ad. This inspired a desire to click and check prices. You clicked, Google got the commission for the click. Brilliant marketing.

It certainly doesn't matter for the Google if your click was of any use to the advertiser.

 

Offline brucehoult

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Re: What's happening in the world of MIPS?
« Reply #43 on: October 15, 2018, 02:42:40 pm »
Marketing doesn't work by predicting purchaser's wishes. It works by controlling purchaser's wishes, which is much more efficient approach.

Mostly I find that I see ads on every site I visit for a product or service I need once or once a year AND BOUGHT YESTERDAY.

Right now, I'm seeing ads everywhere from booking.com for a hotel in Fiji that I already booked on expedia on Saturday. I had checked the price on booking.com as well, just in case it was better.

This is an example of good marketing. You didn't have any desire on checking prices for what you already have. Google showed you the ad. This inspired a desire to click and check prices. You clicked, Google got the commission for the click. Brilliant marketing.

It certainly doesn't matter for the Google if your click was of any use to the advertiser.

No, I checked the price on booking.com before I booked it on expedia.

Google showed me the ad for booking.com after I already had the hotel booked.

I didn't click the ad, google didn't get click commission.
 

Offline Marco

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Re: What's happening in the world of MIPS?
« Reply #44 on: October 15, 2018, 03:41:16 pm »
yup, These algorithms are on made on second order statistic, and they work well for loops.

For loops which loop twice and are still in the BTB next time they loop ...
 

Online legacy

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Re: What's happening in the world of MIPS?
« Reply #45 on: October 16, 2018, 01:35:12 am »
anyway, the intriguing question is now: what happened to R8K? what?!?
you know what! it was that big chip in the prototype suit offered by SGI!

it was a strange beast, with a weird branch prediction unit :-//
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Offline srce

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Re: What's happening in the world of MIPS?
« Reply #46 on: October 19, 2018, 06:51:00 am »
In May, MIPS announced a new 32 bit chip with a new "NanoMIPS" encoding that has 16, 32 and 48 bit opcodes. That looks pretty good too, but it's proprietary as hell and late to the party.
A RISC-V fan talking about being late to the party?  :-DD
 

Online legacy

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Re: What's happening in the world of MIPS?
« Reply #47 on: October 21, 2018, 05:49:04 am »
I wonder who has ever used or seen one of the eval boards made by IDT.



This one was manufactured around the 2000's and looks funny :D



« Last Edit: October 21, 2018, 05:55:26 am by legacy »
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Online nctnico

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Re: What's happening in the world of MIPS?
« Reply #48 on: October 21, 2018, 05:55:01 am »
Offtopic: someone had fun while combining a TQFP and BGA footprint  >:D
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Online legacy

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Re: What's happening in the world of MIPS?
« Reply #49 on: October 21, 2018, 05:56:03 am »
Offtopic: someone had fun while combining a TQFP and BGA footprint  >:D

LOL  :-DD
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