4 ms·

> will add as much as 28 percent more overhead to operations. Yikes. I don't think I'll be enabling that mitigation on my workstation.

bicolao 4y ago
Windows is not affected because it uses IBRS instead, which is less performant than retpoline. So the question is, is IRBS overhead less or more than 28% now?
- mise_en_place 4y ago
  It begs the question, was speculative execution a good idea in the first place?
  - pcwalton 4y ago
    I highly suspect that a comprehensive accounting would show that any basic hardware optimization like speculative execution has saved the total worldwide computing industry hundreds of millions of dollars, if not more. At large scale, optimizations add up to enormous value.
  - pishpash 4y ago
    Compared to what alternative?
    - autoexec 4y ago
      slower processors with more efficient software? For as far as we've come with hardware, the actual user experience hasn't changed anywhere near as dramatically because faster machines just allowed people to push out slower software, the same way that hard drives moving from MBs to GBs to TBs just meant that games and applications bloated up to fill all available disk space and websites bloated up to consume increased bandwidth as we went from 56k to broadband.
      - pcwalton 4y ago
        The reason why games are tens or hundreds of gigabytes in size is that modern textures are high-resolution and models are high in detail; if you took away high-capacity storage, then you'd just end up with worse-looking games. The reason why Web sites are big is largely images, videos, JS, and CSS; if you took away broadband, you'd end up with worse-looking and less functional Web sites. It's like the broken window fallacy in economics: the fact that having limitations gives smart developers an opportunity to work cleverly within them doesn't change the fact that limitations leave everybody worse off overall.
        deleted 4y ago
        [deleted]
        gjs278 4y ago
        autoexec 4y ago
        > The reason why games are tens or hundreds of gigabytes in size is that modern textures are high-resolution and models are high in detail; not "the reason", just "a reason". A lot of it is just laziness. Not compressing audio and video or doing a very poor job of it. For example a Fortnite update took the game from 60GB to 30GB without making it look like garbage so how did they do it? Optimization. Why didn't they do it sooner? Because they didn't care. > The reason why Web sites are big is largely images, videos, JS, and CSS; if you took away broadband, you'd end up with worse-looking and less functional Web sites. Video and images are again "a" reason (and again often the issue is poor compression) but so are bloated JS frameworks, user tracking, and ads. Even very simple websites can bloat to grow larger than full novels. (there are some good examples of this here: https://idlewords.com/talks/website_obesity.htm https://idlewords.com/talks/website_obesity.htm). You could cut the ads and the tracking and the JS bloat without any impact on the content delivered or the functionality. People just don't want to take the effort to lower file sizes which is why people have to turn to things like repackers who can cut the sizes for downloads by more than half. Somehow they manage, and they do it for free no less, but game publishers can't? We could do much better without sacrificing anything (that users care about) in the finished product. If we had to go back to slower processors people would be forced to care enough to write better code and optimize for speed. At least until some new trick for faster speed was developed at which point very little in our lives would be faster, but the code would be slower again.
    - smolder 4y ago
      Could the alternative have been many, simpler cores, and an earlier move to high core counts?
  - nomel 4y ago
    For the metric of performance/Watt and performance/cost, absolutely.
  - zik 4y ago
    It's one of the fundamental techniques that allows high end processors to run fast. If you're happy with a desktop processor that runs at the speed of decades-old processors maybe you don't need it.
  - okanat 4y ago
    Well it is the bread and butter of any consumer CPU after Pentium. If you want to run at the speed of early 90's chips i.e. not even fast enough to play MP3 files without specialized hardware.
usr1106 4y ago
Most workstations run below 10% most of the time. I doubt you will even notice. Where would one expect the worst noticable impact? Number-crunching does not need that many syscalls, so no. Database maybe? It needs syscalls, but is it still CPU-bound? Networking applications?
- nibbleshifter 4y ago
  I run a lot of local VM's on my workstations. I tried offload this workload to the cloud a few times, but that's just not as fast (and cheap) as local VM's. Also requires internet, which I regularly don't have for periods of time. I noticed a huge perf impact on my machines after the spectre mitigations rolled out and had to kill those in the kernel command line.
- pantalaimon 4y ago
  That’s silly, just because system is idle most of the time doesn’t mean performance doesn’t matter when you need it.
throw93232 4y ago
Get refund for your CPU. Clearly broken design, most likely not fixable by microcode update.
- NorwegianDude 4y ago
  I see some are down voting you, but that is an option. If the CPU has a design error then you can return it in many countries. If there is a firmware fix and that fix does not affect performance to a significant degree then it's probably OK. Products should do what the marketing says they should do.
  - userbinator 4y ago
    Products should do what the marketing says they should do. ...which is, that they were never designed to be side-channel-resistant. As early as the 80286 Intel was saying protected mode is not a real security boundary, only a mechanism to avoid accidental errors instead of deliberate maliciousness.

bicolao 4y ago

Windows is not affected because it uses IBRS instead, which is less performant than retpoline. So the question is, is IRBS overhead less or more than 28% now?

mise_en_place 4y ago
It begs the question, was speculative execution a good idea in the first place?
- pcwalton 4y ago
  I highly suspect that a comprehensive accounting would show that any basic hardware optimization like speculative execution has saved the total worldwide computing industry hundreds of millions of dollars, if not more. At large scale, optimizations add up to enormous value.
- pishpash 4y ago
  Compared to what alternative?
  - autoexec 4y ago
    slower processors with more efficient software? For as far as we've come with hardware, the actual user experience hasn't changed anywhere near as dramatically because faster machines just allowed people to push out slower software, the same way that hard drives moving from MBs to GBs to TBs just meant that games and applications bloated up to fill all available disk space and websites bloated up to consume increased bandwidth as we went from 56k to broadband.
    - pcwalton 4y ago
      The reason why games are tens or hundreds of gigabytes in size is that modern textures are high-resolution and models are high in detail; if you took away high-capacity storage, then you'd just end up with worse-looking games. The reason why Web sites are big is largely images, videos, JS, and CSS; if you took away broadband, you'd end up with worse-looking and less functional Web sites. It's like the broken window fallacy in economics: the fact that having limitations gives smart developers an opportunity to work cleverly within them doesn't change the fact that limitations leave everybody worse off overall.
      - deleted 4y ago
        [deleted]
      - gjs278 4y ago
      - autoexec 4y ago
        > The reason why games are tens or hundreds of gigabytes in size is that modern textures are high-resolution and models are high in detail; not "the reason", just "a reason". A lot of it is just laziness. Not compressing audio and video or doing a very poor job of it. For example a Fortnite update took the game from 60GB to 30GB without making it look like garbage so how did they do it? Optimization. Why didn't they do it sooner? Because they didn't care. > The reason why Web sites are big is largely images, videos, JS, and CSS; if you took away broadband, you'd end up with worse-looking and less functional Web sites. Video and images are again "a" reason (and again often the issue is poor compression) but so are bloated JS frameworks, user tracking, and ads. Even very simple websites can bloat to grow larger than full novels. (there are some good examples of this here: https://idlewords.com/talks/website_obesity.htm https://idlewords.com/talks/website_obesity.htm). You could cut the ads and the tracking and the JS bloat without any impact on the content delivered or the functionality. People just don't want to take the effort to lower file sizes which is why people have to turn to things like repackers who can cut the sizes for downloads by more than half. Somehow they manage, and they do it for free no less, but game publishers can't? We could do much better without sacrificing anything (that users care about) in the finished product. If we had to go back to slower processors people would be forced to care enough to write better code and optimize for speed. At least until some new trick for faster speed was developed at which point very little in our lives would be faster, but the code would be slower again.
  - smolder 4y ago
    Could the alternative have been many, simpler cores, and an earlier move to high core counts?
- nomel 4y ago
  For the metric of performance/Watt and performance/cost, absolutely.
- zik 4y ago
  It's one of the fundamental techniques that allows high end processors to run fast. If you're happy with a desktop processor that runs at the speed of decades-old processors maybe you don't need it.
- okanat 4y ago
  Well it is the bread and butter of any consumer CPU after Pentium. If you want to run at the speed of early 90's chips i.e. not even fast enough to play MP3 files without specialized hardware.

usr1106 4y ago

Most workstations run below 10% most of the time. I doubt you will even notice. Where would one expect the worst noticable impact? Number-crunching does not need that many syscalls, so no. Database maybe? It needs syscalls, but is it still CPU-bound? Networking applications?

nibbleshifter 4y ago
I run a lot of local VM's on my workstations. I tried offload this workload to the cloud a few times, but that's just not as fast (and cheap) as local VM's. Also requires internet, which I regularly don't have for periods of time. I noticed a huge perf impact on my machines after the spectre mitigations rolled out and had to kill those in the kernel command line.
pantalaimon 4y ago
That’s silly, just because system is idle most of the time doesn’t mean performance doesn’t matter when you need it.

throw93232 4y ago

Get refund for your CPU. Clearly broken design, most likely not fixable by microcode update.

NorwegianDude 4y ago
I see some are down voting you, but that is an option. If the CPU has a design error then you can return it in many countries. If there is a firmware fix and that fix does not affect performance to a significant degree then it's probably OK. Products should do what the marketing says they should do.
- userbinator 4y ago
  Products should do what the marketing says they should do. ...which is, that they were never designed to be side-channel-resistant. As early as the 80286 Intel was saying protected mode is not a real security boundary, only a mechanism to avoid accidental errors instead of deliberate maliciousness.