1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Intel bug incoming? Meltdown and Spectre exploits

Discussion in 'CPUs' started by pete910, Jan 2, 2018.

Tags:
  1. FredFlint

    Wise Guy

    Joined: Feb 1, 2006

    Posts: 1,797

    The software I write for work will probably take a big hit from this as it's file IO and network limited, and it looks like that's what gets the biggest hit. The VM's run at close to 100% before the patch:(
     
  2. Dougsnake

    Mobster

    Joined: Oct 18, 2002

    Posts: 2,996

    Location: west yorkshire

    well looks like asus have updated the bios for mine but think ill sit on it a while to see what the aftermath is like :p
     
  3. DarkBahamut

    Gangster

    Joined: Mar 24, 2011

    Posts: 434

    If your CPU is the Ivybridge CPU in your sig then there isn't an update. There are only updates as far back as Haswell so far. The file includes microcode for all the CPU's listed, but only Haswell and newer are Spectre patched ones. The release notes files included will detail the updated microcode files.
     
  4. TrixP10

    Associate

    Joined: May 26, 2017

    Posts: 30

    Just my two penneth,
    if at present large Intel customers are held in place by 'sweetner deals - replacement contracts etc. then surely this latest security debacle would render those contracts void (equipment not fit for purpose).

    Time to squeeze Intel's testicles (or even kick them)
     
  5. AmateurExpert

    Gangster

    Joined: Aug 7, 2017

    Posts: 296

    Location: location location

    With the flood of articles I can't find the exact article that I had in mind, but here are similar results:

    Here's Realbench, and TechSpot's storage benchmarks impacted.

    The performance impacts also show up (though inevitably to a lesser extent) at the application level - Computerbase.de benchmarks.

    Here's the Retpoline impact on Linux too.

    Here's a good article on ArsTechnica on how the various patches are impacting performance - it's worth reading.
     
  6. AmateurExpert

    Gangster

    Joined: Aug 7, 2017

    Posts: 296

    Location: location location

    Maybe, but Intel's lawyers might be even sharper than their engineers.
     
  7. AmateurExpert

    Gangster

    Joined: Aug 7, 2017

    Posts: 296

    Location: location location

    To follow up on the ArsTechnica article and Spectre performance impacts, this is an interesting comment from a missive from one of the DragonflyBSD kernel devs:

    DragonflyBSD is harder hit than either Windows or Linux, but the performance hit is real and needs to be addressed. From the end-users' perspective, many will be fortunate in that in their use cases much of the performance loss is either masked by other bottlenecks or in areas where it won't be noticed.
     
  8. TrixP10

    Associate

    Joined: May 26, 2017

    Posts: 30

    Good articles . . . . but I still cannot find anything that breaks down the performance degradation of Meltdown vs Spectre. At this point, making an assumption that mitigating Spectre (alone) will have bigger performance issues than mitigating Meltdown + Spectre is wrong.

    "Zen's branch predictor, however, is a bit different. AMD says that its predictor always uses the full address of the branch; there's no flattening of multiple branch addresses onto one entry in the BTB. This means that the branch predictor can only be trained by using the victim's real branch address. This seems to be a product of good fortune; AMD switched to a different kind of branch predictor in Zen (like Samsung in its Exynos ARM processors, AMD is using simple neural network components called perceptrons), and the company happened to pick a design that was protected against this problem."


    I am sure that there are issues still to address but blanket fud without evidence seems like Intel PR.
     
  9. TrixP10

    Associate

    Joined: May 26, 2017

    Posts: 30

    That's very true, but there are many customer who can afford some very sharp lawyers and will have a very good case - in or out of court.
     
  10. drunkenmaster

    Caporegime

    Joined: Oct 18, 2002

    Posts: 32,078

    The only thing it gets kinda wrong is that the performance won't all come back, because the fix is doing things that include the checks it should do for meltdown, the spectre 2 fix, if done as AMD does which makes the risk of a successful attack almost non existent shouldn't really decrease performance, hiding the BTB entries in unpredictable locations shouldn't hit performance, though it's not strictly speaking a full fix. I'm not sure what AMD are doing for variant 2 with their patch but it appears to be small, negligible performance hit and they are convinced it reduces attack chance to zero.

    Either way, a 'fixed' Skylake won't be as fast as current Skylake without any of the fixes/patches in place, it will be at least a few percent slower, maybe 4-5% total.

    So best case they have this fixed by their first 10nm desktop chips(extremely unlikely imo) then we'll have Intel basically losing performance but gaining core count, probably matching AMD by making mainstream CPU only with at least 8 core and by all accounts losing a little clock speed vs 14nm++. AMD will be gaining a huge chunk of clock speed, gaining a decent IPC gain, going to seemingly 12 core and at the same time reducing die size vs current Ryzen meaning increased margins while we also get faster chips. AMD is going to have a very very good 2019.
     
  11. Perfect_Chaos

    Mobster

    Joined: Aug 26, 2004

    Posts: 3,488

    Location: In dem hills

    Too bad we have to wait a bit for the most interesting part of this between AMD and Intel, that is how close the zen 2 chips will compare to Intel's.

    Gonna be a bit of a wait to see what that new supposed revolutionary CPU is from Intel too.
     
  12. pete910

    Wise Guy

    Joined: Oct 3, 2013

    Posts: 1,827

    Not seen any data for AMD on that tbh, the microcode updates etc are optional. They seem fairly adamant that the chances are just about negligible of actually being effected.
     
  13. AmateurExpert

    Gangster

    Joined: Aug 7, 2017

    Posts: 296

    Location: location location

    My point was that even though Ryzen doesn't need a redesign to tackle Meltdown, the performance hit from the Spectre software mitigations in some cases is not negligible for Ryzen (though some Intel kit seems to get hit worse - but I wasn't talking about Intel), and this is even before AMD have supplied microcode updates to facilitate OS-level Spectre Variant 2 mitigations. Therefore there is still an opportunity for AMD to change future chips to give back some performance in these areas - whether through negating the need for the software workarounds or otherwise.

    I don't believe I made any assumptions or arguments that Spectre performance issues are bigger than Meltdown+Spectre (I don't see how that could make sense?). In an earlier post I did say: "This suggests that (for the game sequences in the video at least) the Spectre mitigation (IBRS - microcode + OS patch for Variant 2 CVE-2017-5715) has negligible impact, whereas the Meltdown mitigation has some. However, without an equivalent microcode update for AMD, I don't know whether Spectre Variant 2 mitigation on Windows will have a similar sort of impact.".

    ?

    Even without the microcode updates, the patches to the Linux kernel so far have impacted Ryzen and EPYC. Maybe there'll be strong enough proof that Ryzen etc. are not vulnerable to Spectre and so allow them an exception from the mitigations (as with Meltdown), but until then the default is to take the hit.
     
  14. Cromulent

    Wise Guy

    Joined: Nov 1, 2007

    Posts: 2,345

    I rang the Citizens Advice Bureau about this yesterday and apparently you do have some rights if the product is not performing as originally stated due to the patches. You first need to talk to the people who sold you the hardware directly. The option seems to be for a full but if any computer you buy is going to suffer from the same issue I'm not sure returning the computer will be much of an option. Having said that you do have rights as consumers and you should speak to the people you bought the hardware from. If you paid by credit card and the seller isn't playing ball then you can talk to your credit card company who are also liable if the item cost more than £100.

    I'm highly tempted to talk to the people I bought my hardware from as it is a new computer and this is unacceptable that I should pay so much and then get such a massive performance penalty. If anyone is interested in doing the same let me know and we can try and help each other. Due to OCUK forum rules though I am not able to mention any company names.

    If you are a business this doesn't include you as business transactions are handled under different legislation.
     
  15. Mercutio

    Mobster

    Joined: Jun 11, 2003

    Posts: 4,089

    Location: Sheffield, UK

    I'm right in assuming Sandybridge will remain unpatched and I should go full updates, riot shields and ablative armour going forward?
    I take it my performance hit is in the 20%+ region too?
    Only need to make it till April thankfully.
     
  16. Perfect_Chaos

    Mobster

    Joined: Aug 26, 2004

    Posts: 3,488

    Location: In dem hills

    @Cromulent i got my 5820k here at OCUK, not sure they would do anything about this though. Saying that, they did for the whole Nvidia 970 issue.
     
  17. Cromulent

    Wise Guy

    Joined: Nov 1, 2007

    Posts: 2,345

    Find out how long the warranty is for the Intel CPU you bought and if it is still in warranty I think you might have some luck as it is clearly defective and the fix reduces the performance it was sold as having.
     
  18. Perfect_Chaos

    Mobster

    Joined: Aug 26, 2004

    Posts: 3,488

    Location: In dem hills

    I bought it in March 2015, says it has a 3 year warranty on the site so i guess it's still in warranty then. Same as the board, i bought both together as a bundle.
     
  19. Drollic

    Wise Guy

    Joined: Feb 24, 2013

    Posts: 2,280

    Location: East Midlands

    Returns aren't much good when there's no other alternative available yet? Money back and no PC?
     
  20. Perfect_Chaos

    Mobster

    Joined: Aug 26, 2004

    Posts: 3,488

    Location: In dem hills

    That's true and there isn't really much in the way of alternatives, i do have some x58 parts hanging about to use.. not sure if that would be worth using in the meantime.
     


Share This Page