Next Generation Hardware Speculation with a Technical Spin [post GDC 2020] [XBSX, PS5]

Discussion in 'Console Technology' started by Proelite, Mar 16, 2020.

  1. RobertR1

    RobertR1 Pro
    Legend

    Joined:
    Nov 2, 2005
    Messages:
    5,725
    Likes Received:
    901
    Glad it's more official now that someone from DF has said it. :)

    Called it way early when I said, devs will work to a known spec and won't be relaying on "boost"
     
    BRiT likes this.
  2. PSman1700

    Veteran Newcomer

    Joined:
    Mar 22, 2019
    Messages:
    2,341
    Likes Received:
    725
    Yes, he said it before though, think it was yesterday, and today on this forum. Its what i was trying to say but he does it so much better :p
     
  3. JoeJ

    Regular Newcomer

    Joined:
    Apr 1, 2018
    Messages:
    942
    Likes Received:
    1,059
    Now i'm not sure how much sarcasm there is in the sentence.
    But i give an example: The realtime GI stuff i'm currently working on can actually not saturate the Vega GPU i'm using. The test scene is quite small, but to compensate i set all settings to 'ultra'. It takes 2ms which is fine. Then i look at GPU clocks and i see it keeps running at 166 MHz and is totally bored.
    The example is not very practical - in a game this task would run async with other work. But there are situations where no max clock is necessary, similar to how it rarely happens all CPU cores run at 100%.
    Why not making the other part faster if this happens? It's no bad thing to have dynamic clocks - it's an additional option.
     
    PSman1700 likes this.
  4. BRiT

    BRiT Verified (╯°□°)╯
    Moderator Legend Alpha

    Joined:
    Feb 7, 2002
    Messages:
    14,897
    Likes Received:
    13,028
    Location:
    Cleveland
    It all depends on how low the CPU needs to clock for the GPU to MAX, and vice-versa.
     
    Proelite and PSman1700 like this.
  5. bgroovy

    Regular Newcomer

    Joined:
    Oct 15, 2014
    Messages:
    799
    Likes Received:
    626
    I don't know how it works! Factor it in anyway!

    The thing is, BCPack IS factored in. We know the compression chip maxes its output at 6GB/s. The PS5 compression chip output maxes at 22GB/s. Both are best case figures. PS5's RAW throughput is near the XSX's best case output. There is no chance that BCPack provides an advantage that is being missed.

    There's no indication at this point the PS5 can run with SMT disabled.

    That's not what it was advertised as.

    Which we've been told is very rare.

    Dictator is talking out his ass. This is explicitly the opposite of what Cerny says happens. DF are not an official source when they are going on about their pet theories.
     
    disco_ and Arwin like this.
  6. PSman1700

    Veteran Newcomer

    Joined:
    Mar 22, 2019
    Messages:
    2,341
    Likes Received:
    725
    Very much of it so :)

    You never know, we don't have all the technical info and plans yet, from either i think.

    True we could say there are no dynamic clocks, if its that rare its nothing to worry about really.

    Source? your ass? :p
     
  7. 3dilettante

    Legend Alpha

    Joined:
    Sep 15, 2003
    Messages:
    8,348
    Likes Received:
    3,882
    Location:
    Well within 3d
    That's what I mean by the SSD situation being the reverse of the DRAM situation for the PS5 and Xbox SX. The Xbox has a raw throughput advantage with a possible caveat in capacity/arrangement in DRAM, while the PS5 has that for its SSD and compressor.
     
    PSman1700 likes this.
  8. bgroovy

    Regular Newcomer

    Joined:
    Oct 15, 2014
    Messages:
    799
    Likes Received:
    626
    We have all we need: The theoretical maximums. He is positing a situation where BCPack would have to magically exceed the capabilities of the hardware to confer his dreamed of advantage.

    Mark Cerny. He gave a talk this week.
     
    disco_ likes this.
  9. bgroovy

    Regular Newcomer

    Joined:
    Oct 15, 2014
    Messages:
    799
    Likes Received:
    626
    What possible caveat for the PS5 SSD? Other than the total capacity being smaller it is straight up faster in every way we know of.
     
  10. BRiT

    BRiT Verified (╯°□°)╯
    Moderator Legend Alpha

    Joined:
    Feb 7, 2002
    Messages:
    14,897
    Likes Received:
    13,028
    Location:
    Cleveland
    Can everyone please take a deep breath and calm down? Let's keep things civil. Being hostile and confrontational is no way to conduct an open technical discussion. Escalations never work out well for anyone.
     
  11. RobertR1

    RobertR1 Pro
    Legend

    Joined:
    Nov 2, 2005
    Messages:
    5,725
    Likes Received:
    901
    There seems to be a general confusion on here about not being able to distinguish between clock speed and current. Not saying it’s you, just speaking in general.

    The load you put in at a given frequency will determine the voltage needed and thus the power draw.

    Let’s say a cpu doing 3ghz pulling 20amps at 1v is generating 20w of power draw. 20w is it’s max budget. We won’t go into vrm complications on here.

    Lets drop that down to 10amps. There no reason for the frequency to drop as it’s below the max power budget. So at 10 amp load the cpu is happily signing along at 3ghz (max set) drawing 10w.

    Now a 25amp load comes in. Because you’re power throttling, your cpu frequency will drop as needed until ”voltage x amps = max power draw.” That’s the “boost” part.

    In this situation, it’s actually reverse boost meaning its controlling frequency drop from best case scenario based on load coming in and the power budget allocated.
     
    mpg1, BRiT and JoeJ like this.
  12. PSman1700

    Veteran Newcomer

    Joined:
    Mar 22, 2019
    Messages:
    2,341
    Likes Received:
    725
    Yes, but nothing cerney said conradicts what DF/Dictator explained.
     
    Proelite and pharma like this.
  13. BRiT

    BRiT Verified (╯°□°)╯
    Moderator Legend Alpha

    Joined:
    Feb 7, 2002
    Messages:
    14,897
    Likes Received:
    13,028
    Location:
    Cleveland
    So is it correct to say the following?

    In this situation the CPU and GPU are part of 1 single unit that has an upper power draw limit. So if the GPU portions are mostly maxed out drawing the majority of the power, you have less power to allocate to the CPU.

    It would be useful if there was a chart or appendix of empirical measurements of CPU and GPU instruction mixes and what impact it has on the timings. Since the frequencies will vary, the latencies of the instructions would vary too.

    Maybe even a listing of instructions or instruction mixes and their power draw impacts.
     
  14. AbsoluteBeginner

    Regular Newcomer

    Joined:
    Jun 13, 2019
    Messages:
    764
    Likes Received:
    977
    So I just thought I should look into how well does RDNA scale with clocks and here is actually interesting benchmark on YT with 5700 (36CU) and 5700 (XT).

    In this case, 5700 is clocked at 2150MHz (9.9TF) and 5700XT is clocked at 1750MHz (8.9TF).



    Results are surprising because it seems XT pulls ahead most of the time, and sometimes not even by a little, even though it has 400MHz and 1TF deficit. Not sure what to make of this really...
     
    xpea and PSman1700 like this.
  15. 3dilettante

    Legend Alpha

    Joined:
    Sep 15, 2003
    Messages:
    8,348
    Likes Received:
    3,882
    Location:
    Well within 3d
    The caveat is primarily the smaller capacity, and if the BCPack algorithm has the stated advantage on game content there is an additional capacity disparity. On top of that, if the BCPack algorithm has that level of advantage, it would increase the mix of higher-compression assets being read by the SSD versus one using zlib or Kraken.
    That average also depends on how much the Series X can apply BCPack versus zlib, which is something I likened to a slower/faster divide in the storage.

    In both cases, I think the signs point to the platform with the raw capability having an edge despite having some disadvantages.
     
    blakjedi, Remij, PSman1700 and 4 others like this.
  16. MrFox

    MrFox Deludedly Fantastic
    Legend Veteran

    Joined:
    Jan 7, 2012
    Messages:
    6,332
    Likes Received:
    5,662
    It's ambiguous at best. Cerny said the gpu and cpu would run at the max clock, or close to, the majority of the time. Saying dev will have to chose between cpu power and gpu power is in conflict with the presentation, unless the majority of the time means to include optimizations from devs to micro-manage every last percentage.

    Again, we are all talking out of our asses since we don't have reasonable real world examples of how often and by how much the frequency drops, and whether the devs manage this or not. HOWEVER the presentation wording suggests against this with "majority of the time", and "very small drop since 2% drop is 10% less power".
     
    BRiT likes this.
  17. MrFox

    MrFox Deludedly Fantastic
    Legend Veteran

    Joined:
    Jan 7, 2012
    Messages:
    6,332
    Likes Received:
    5,662
    How do both consoles handle lossy data?

    We had LZ for lossless and JPG for lossy, but now we only have lossless or did I miss a big part? Kraken seems to have both modes?
     
    #617 MrFox, Mar 20, 2020
    Last edited: Mar 20, 2020
  18. Jay

    Jay
    Veteran Regular

    Joined:
    Aug 3, 2013
    Messages:
    2,472
    Likes Received:
    1,573
    Where is the data (as it is) coming from regarding Bcpack?
     
  19. bgroovy

    Regular Newcomer

    Joined:
    Oct 15, 2014
    Messages:
    799
    Likes Received:
    626
    Other than Cerny saying the GPU and CPU both run at their max clocks almost always? Dictator is claiming max clocks are an exclusive choice, one of the other. That's not how it works at all.
     
  20. BRiT

    BRiT Verified (╯°□°)╯
    Moderator Legend Alpha

    Joined:
    Feb 7, 2002
    Messages:
    14,897
    Likes Received:
    13,028
    Location:
    Cleveland
    "majority of the time" <> 'almost always'
     
    egoless, PSman1700 and function like this.
Loading...

Share This Page

  • About Us

    Beyond3D has been around for over a decade and prides itself on being the best place on the web for in-depth, technically-driven discussion and analysis of 3D graphics hardware. If you love pixels and transistors, you've come to the right place!

    Beyond3D is proudly published by GPU Tools Ltd.
Loading...