[plug] Ryzen

[Brad Campbell]

On 01/04/17 17:57, Brad Campbell wrote:

> I upgraded to 4.11-rc4 and it seems to have gone away, having survived a
> 13 hour RAID check and 7 hours of networked file transfer, I'm going to
> press send on this and see if it crashes.

So just an update for those following alone at home, it did crash about 
30 minutes after I pressed send.

Nothing wrong with the kernel. The problem was RAM. Specifically RAM 
listed in the ASUS QVL for the board and running at the 
recommended/specified settings. It took pathological stress loads to 
manifest, but after over a week of fighting it I decided to buy new RAM 
and the problem has magically gone away.

Old ram. Listed on QVL. Has bright blue heat-spreader and XMP ricer 
profiles. Relatively expensive.

New ram. Basic green PCB, no ricer profiles, sold by a subsidiary of the 
manufacturer (Crucial & Micron respectively). Cheap. Unable to fault it 
so far and it has survived every conceivable test I can throw at it for 
about 36 hours now.

To give you some idea of what was required to make it fail, I was 
simultaneously running Prime95

: mprime -t

  - a looping kernel compile

: while true ; do make distclean ; make allyesconfig ; make -j16 ; done

- Multiple periodic cpuburn instances

: while true ; do for i in `seq 16` ; do burnP6 & done ; sleep 30 ; 
killall burnP6 ; sleep 300 ; done

And I could still only get it to fail after a couple of kill / respawn 
of the mprime instance.

This is an insidious incompatibility. It'd pass 24 hours of memtest86+, 
24 hours of mprime -t, or 24 hours of looping kernel compiles. It wasn't 
until I started combining them and killing/respawning Prime95 that I 
could get it to fail consistently (and that could be 30 seconds to 4 hours).

There are *lots* of issues with RAM compatibility with Ryzen. It's 
supposedly getting better, but be careful.

Other than that, my original assessment stands. Core for core it's about 
as fast as my fairly overclocked i7-3770K but with twice as many cores, 
and double the L3.

Software compiles fly. Windows under KVM is _quick_. All in all, a nice 
upgrade if you can weather the loss of hair.


-- 
Dolphins are so intelligent that within a few weeks they can
train Americans to stand at the edge of the pool and throw them
fish.