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Ryzen CPU HyperThreads break if 100% busy and interrupted to top of Memory

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Re: Ryzen CPU HyperThreads break if 100% busy and interrupted to top of Memory

#21

Post by stefantalpalaru »

krylon wrote: post #20

I bought a custom-built Rzyen-based PC around Easter, and I have experienced some issues with it; I am not sure, though, were to put the blame (CPU, motherboard/firmware, operating system (which is openSUSE Tumbleweed)). Under heavy load, the machine has performed most gracefully. However, the machine does freeze (almost) completely when left idle for a while (usually > 1 hour). When it happens, it sometimes still re…

> However, the machine does freeze (almost) completely when left idle for a while (usually > 1 hour).

Try disabling the C6 power state from BIOS: https://www.reddit.com/r/hardware/comments/6rklcf/ryzen_segf...

Re: Ryzen CPU HyperThreads break if 100% busy and interrupted to top of Memory

#23

Post by loeg »

0x0 wrote: post #10

Not the first bug reported for Ryzen. Wasn't there a couple of others too, one with linux locking up and another triggered by the ocaml compiler emitting opcodes refering AH/BH/CH/DH registers in a tight loop? Edit: Sorry, the ocaml bug was Intel Skylake. It's interesting how so many new CPUs have breaking bugs. Feels like it's been quiet since the original pentium F00F bug and then all of a sudden everyone's new CPU…

> It's interesting how so many new CPUs have breaking bugs.

Dan Luu observed the same thing, and thinks it will continue to be very likely: https://danluu.com/cpu-bugs/

Re: Ryzen CPU HyperThreads break if 100% busy and interrupted to top of Memory

#24

Post by mjevans »

sqeaky wrote: post #9

Does this affect only BSDs then? I have a Ryzen machine I bought and put into a Jenkins cluster. It does builds on a bunch of VMs occasionally and pegs the CPUs. I have had no issue so far.

It probably affects Windows and every other OS as well. It's just less likely to be seen by their typical user workloads, or more likely to be written off as some other issue when it does happen.

Re: Ryzen CPU HyperThreads break if 100% busy and interrupted to top of Memory

#25

Post by krylon »

stefantalpalaru wrote: post #21
krylon wrote: post #20

I bought a custom-built Rzyen-based PC around Easter, and I have experienced some issues with it; I am not sure, though, were to put the blame (CPU, motherboard/firmware, operating system (which is openSUSE Tumbleweed)). Under heavy load, the machine has performed most gracefully. However, the machine does freeze (almost) completely when left idle for a while (usually > 1 hour). When it happens, it sometimes still re…

> However, the machine does freeze (almost) completely when left idle for a while (usually > 1 hour). Try disabling the C6 power state from BIOS: https://www.reddit.com/r/hardware/comments/6rklcf/ryzen_segf...

Thanks for the hint!

Re: Ryzen CPU HyperThreads break if 100% busy and interrupted to top of Memory

#26

Post by theandrewbailey »

stefantalpalaru wrote: post #21
krylon wrote: post #20

I bought a custom-built Rzyen-based PC around Easter, and I have experienced some issues with it; I am not sure, though, were to put the blame (CPU, motherboard/firmware, operating system (which is openSUSE Tumbleweed)). Under heavy load, the machine has performed most gracefully. However, the machine does freeze (almost) completely when left idle for a while (usually > 1 hour). When it happens, it sometimes still re…

> However, the machine does freeze (almost) completely when left idle for a while (usually > 1 hour). Try disabling the C6 power state from BIOS: https://www.reddit.com/r/hardware/comments/6rklcf/ryzen_segf...

I'll definitely try this. I downgraded my latest BIOS because I couldn't stand the random crashes that had no rhyme or reason (crashed during gaming, youtube, encrypting my drives, emailing, browsing, among other activities).

Re: Ryzen CPU HyperThreads break if 100% busy and interrupted to top of Memory

#28

Post by rbisewski »

I had a similar scenario occur on my Ryzen 1700 w/ Gigabyte B350 Motherboard. Nothing in the BIOS seemed to help, and updating to the latest version of the firmware didn't seem to help much.

Eventually I just looked into some kernel docs decided that setting the IOMMU mode to pt during bootup might work. Specifically, I added the following to my grub config.

GRUB_CMDLINE_LINUX_DEFAULT="quiet iommu=pt"

Not sure if this will help any of you, but it did completely eliminate the problems I had.

Shameless plug, wrote a blog about my investigations into it:

https://ibiscybernetics.com/blog/2017-05-24.html

Re: Ryzen CPU HyperThreads break if 100% busy and interrupted to top of Memory

#29

Post by paulmd »

StillBored wrote: post #15

Its like we have all collectively forgotten that the first release of a hardware or software project is just an expensive beta. I don't buy 1st gen microarches because i'm not interested in paying top dollar to be a tester. What I find odd, is that apparently both intel and AMD have also forgotten this, as Intel seems to be moving toward making their enterprise customers the beta testers, while AMD seems so desperate…

AMD's not doing a recall, it works decently enough for most applications. Their response is going to be "if it crashes your application, turn SMT off".

Consider they didn't even do a recall when Phenom had a showstopping TLB bug, they shipped a BIOS patch that disabled TLB entirely.

And remember, Epyc is on a new stepping of the silicon, it's possible this is already fixed on it. (Threadripper is not, however)

Re: Ryzen CPU HyperThreads break if 100% busy and interrupted to top of Memory

#30

Post by sondr3 »

I'm thinking of building a new PC this autumn or spring but news like this about the new AMD processors are making me a bit uneasy committing to them. I don't think bugs like this and the one with GCC crashing (might be the same) might affect me but it's a risk I'm not sure if I want to take.
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