On Wed, Mar 18, 2020 at 02:02:08PM -0700, Gregory Nowak wrote:
> On Wed, Mar 18, 2020 at 06:24:27PM +0100, Antony Stone wrote:
> > Does anyone here have experience of running Devuan on AMD Ryzen CPUs?

Similar results on 2990WX (a gen older).

With systemd, there's a hard power-off (with a nasty screech from the fan)
somewhere late during boot. Not a squeal on serial, _usually_ physical
poweroff (G3 not G2) helps but after a case it didn't help I'm not digging
harder.

Without systemd, everything works perfectly, including any tests I could
think of.

> > I'm just planning to get a new PC, and I've generally preferred AMD to Intel,

High core-count AMDs _suck_. They have so poor memory and
chiplet-to-chiplet bandwidth that in most loads I tried a much smaller Intel
beats them easily.

For example, a simple multithreaded task:
* 64 threads: 12000 seconds
* 16 threads (numactl -N 0): 9000 seconds
* a 6700K Skylake: 1200 seconds
* a 2*56-thread server, -N 0: somewhere near geometric average of the two
above

(Disclaimer: I work at one of these companies, and that's not AMD.)

> > so just wondering whether there's anything I need to look out for with pretty
> > much the latest hardware.
>
> Yes:
>

> 1. Upgrade your kernel to 4.10 or later. If you install the kernel
>    from Beowulf-backports, that should be good enough. 

For me, even with 5.6-rc6 doesn't make the problem disappear.

Thus, it's possible there are _multiple_ bugs in systemd where it pokes into
places it shouldn't poke into.

Meow!
-- 
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⣾⠁⢠⠒⠀⣿⡁ in the beginning was the boot and root floppies and they were good.
⢿⡄⠘⠷⠚⠋⠀                                       -- <willmore> on #linux-sunxi
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