5 ms·

From what I've read, this slowdown only affects syscalls, which, since they aren't usually a huge percentage of processing in the first place, should not have s

From what I've read, this slowdown only affects syscalls, which, since they aren't usually a huge percentage of processing in the first place, should not have such an effect. You're more likely looking at a few percent at most, which is not going to be enough to make AMD outperform Intel. Let's stop the fear mongering and wait for actual metrics.

mschaef 9y ago
> syscalls, which, since they aren't usually a huge percentage of processing in the first place... Let's stop the fear mongering Agreed! (We should probably also stop overgeneralizing about the nature of computational workloads.)
vardump 9y ago
> From what I've read, this slowdown only affects syscalls Incorrect. It also affects interrupts and (page) faults. Any usermode to kernel and back transition.
- api 9y ago
  So this is evil for virtualization hosting, which is the major enterprise application for Intel chips. Hosting on bare metal will become more attractive. Too bad you can't long OVH and Hetzner.
  - chrisper 9y ago
    >Too bad you can't long OVH and Hetzner. What does that even mean? Also Hetzner just introduced some AMD Epyc server.
    - golfer 9y ago
      "Long" as a verb means to purchase their stock. As opposed to "shorting" a stock, which means making a bet that it will go down in value.
      - chrisper 9y ago
        Ah that makes sense. Thanks!
  - rbjorklin 9y ago
    For some reason I can’t reply to ‘chrisper’ but I think ‘api’ is referring to going long in the stock market. https://www.investopedia.com/terms/l/long.asp https://www.investopedia.com/terms/l/long.asp
    - Splines 9y ago
      > For some reason I can’t reply to ‘chrisper’ HN doesn't let you do this to new comments to avoid back-and-forth commenting that is typical in flamewars.
      - sli 9y ago
        Coming up on 9 years here and I'm still finding out new things about how this site works. I've been wondering recently why some comments aren't replyable.
        jfoutz 9y ago
        I think there is a time delay. Wait a few minutes or hours and you can reply. That cooling off period has helped me really think through my replies.
        AnimalMuppet 9y ago
        They become replyable after some amount of time. The amount of time varies based on how active the thread is and/or how deeply nested the comment is. You can reply anyway, but you have to click on the timestamp ("X minutes ago") to do it.
      - pbhjpbhj 9y ago
        Usually you can click on the <posting time> and go to a page that displays only that comment, which has a reply box even when there's no reply option on the main page.
- bandrami 9y ago
  That 100Hz timer tunable just got a lot more attractive...
- dx034 9y ago
  Does that mean that you can get an instance on AWS and slowdown the underlying server for all others by forcing a lot of syscalls? Or how is performance distributed between tenants?
DocSavage 9y ago
Prelim benchmarks show a significant impact (~20%) on Postgresql benchmarks.
- paulmd 9y ago
  20% when running SELECT 1; over a loopback network interface, not in real-world workloads. The other benchmark that has generated some consternation is running 'du' on a nonstop loop. Both of these situations are pathological cases and don't reflect real-world performance. My guess is a 5-10% performance hit on general workloads. Still significant, but nowhere near as bad as some of the numbers that are getting thrown around. And, databases are the worst case scenario, most real-world applications are showing 1% performance impact or less. https://www.computerbase.de/2018-01/intel-cpu-pti-sicherheitsluecke/ https://www.computerbase.de/2018-01/intel-cpu-pti-sicherheit... https://www.hardwareluxx.de/index.php/news/hardware/prozessoren/45319-intel-kaempft-mit-schwerer-sicherheitsluecke-im-prozessor-design.html https://www.hardwareluxx.de/index.php/news/hardware/prozesso...
  - ricardobeat 9y ago
    Why should we trust your guesses over numbers being thrown around? Your last link is all gaming benchmarks, which as the article mentions are not affected much.
  - eberkund 9y ago
    It's not really a worst case scenario when you consider where the majority of Intel's revenue comes from: selling their high margin server chips for use in data centers, a significant portion of which are running some kind of database.
- sllabres 9y ago
  Another quick postgres estimate [1] with lower impact and a a reply from Linus Torvalds that this values are in the range what they are expecting from the patch. "... Something around 5% performance impact of the isolation is what people are looking at. ..." [2] [1] http://lkml.iu.edu/hypermail/linux/kernel/1801.0/01274.html http://lkml.iu.edu/hypermail/linux/kernel/1801.0/01274.html [2] http://lkml.iu.edu/hypermail/linux/kernel/1801.0/01299.html http://lkml.iu.edu/hypermail/linux/kernel/1801.0/01299.html
hinkley 9y ago
Software development workflows have some of the worst syscall profiles out there. This is going to hit most of us where we live.

mschaef 9y ago

> syscalls, which, since they aren't usually a huge percentage of processing in the first place... Let's stop the fear mongering Agreed! (We should probably also stop overgeneralizing about the nature of computational workloads.)

vardump 9y ago

> From what I've read, this slowdown only affects syscalls Incorrect. It also affects interrupts and (page) faults. Any usermode to kernel and back transition.

api 9y ago
So this is evil for virtualization hosting, which is the major enterprise application for Intel chips. Hosting on bare metal will become more attractive. Too bad you can't long OVH and Hetzner.
- chrisper 9y ago
  >Too bad you can't long OVH and Hetzner. What does that even mean? Also Hetzner just introduced some AMD Epyc server.
  - golfer 9y ago
    "Long" as a verb means to purchase their stock. As opposed to "shorting" a stock, which means making a bet that it will go down in value.
    - chrisper 9y ago
      Ah that makes sense. Thanks!
- rbjorklin 9y ago
  For some reason I can’t reply to ‘chrisper’ but I think ‘api’ is referring to going long in the stock market. https://www.investopedia.com/terms/l/long.asp https://www.investopedia.com/terms/l/long.asp
  - Splines 9y ago
    > For some reason I can’t reply to ‘chrisper’ HN doesn't let you do this to new comments to avoid back-and-forth commenting that is typical in flamewars.
    - sli 9y ago
      Coming up on 9 years here and I'm still finding out new things about how this site works. I've been wondering recently why some comments aren't replyable.
      - jfoutz 9y ago
        I think there is a time delay. Wait a few minutes or hours and you can reply. That cooling off period has helped me really think through my replies.
      - AnimalMuppet 9y ago
        They become replyable after some amount of time. The amount of time varies based on how active the thread is and/or how deeply nested the comment is. You can reply anyway, but you have to click on the timestamp ("X minutes ago") to do it.
    - pbhjpbhj 9y ago
      Usually you can click on the <posting time> and go to a page that displays only that comment, which has a reply box even when there's no reply option on the main page.
bandrami 9y ago
That 100Hz timer tunable just got a lot more attractive...
dx034 9y ago
Does that mean that you can get an instance on AWS and slowdown the underlying server for all others by forcing a lot of syscalls? Or how is performance distributed between tenants?

DocSavage 9y ago

Prelim benchmarks show a significant impact (~20%) on Postgresql benchmarks.

paulmd 9y ago
20% when running SELECT 1; over a loopback network interface, not in real-world workloads. The other benchmark that has generated some consternation is running 'du' on a nonstop loop. Both of these situations are pathological cases and don't reflect real-world performance. My guess is a 5-10% performance hit on general workloads. Still significant, but nowhere near as bad as some of the numbers that are getting thrown around. And, databases are the worst case scenario, most real-world applications are showing 1% performance impact or less. https://www.computerbase.de/2018-01/intel-cpu-pti-sicherheitsluecke/ https://www.computerbase.de/2018-01/intel-cpu-pti-sicherheit... https://www.hardwareluxx.de/index.php/news/hardware/prozessoren/45319-intel-kaempft-mit-schwerer-sicherheitsluecke-im-prozessor-design.html https://www.hardwareluxx.de/index.php/news/hardware/prozesso...
- ricardobeat 9y ago
  Why should we trust your guesses over numbers being thrown around? Your last link is all gaming benchmarks, which as the article mentions are not affected much.
- eberkund 9y ago
  It's not really a worst case scenario when you consider where the majority of Intel's revenue comes from: selling their high margin server chips for use in data centers, a significant portion of which are running some kind of database.
sllabres 9y ago
Another quick postgres estimate [1] with lower impact and a a reply from Linus Torvalds that this values are in the range what they are expecting from the patch. "... Something around 5% performance impact of the isolation is what people are looking at. ..." [2] [1] http://lkml.iu.edu/hypermail/linux/kernel/1801.0/01274.html http://lkml.iu.edu/hypermail/linux/kernel/1801.0/01274.html [2] http://lkml.iu.edu/hypermail/linux/kernel/1801.0/01299.html http://lkml.iu.edu/hypermail/linux/kernel/1801.0/01299.html

hinkley 9y ago

Software development workflows have some of the worst syscall profiles out there. This is going to hit most of us where we live.