Solved Disk/ZFS hangs until I switch to console

L

laufdi

Occasionaly, I think at high disk activities, everything hangs and some windows don't get redrawn, it seems that disk access is somehow blocked. Until I switch to console by Ctrl-Alt-F?, when everything continues to work. I can then go back to the X screen and wait for the next hang.

This is since somewhere in 10.0-STABLE, now 10.1-STABLE, amd64, and xorg with nvidia-driver on a ZFS filesystem on SSD. Any ideas?
 
Tested RAM with memtest86+. I have 2 x 4 GB. All OK except when I use SMP mode with both modules inserted. Then it hangs. Single processor mode and single module SMP is all OK... So I don't know which is bad. :( The modules are also different, maybe that's the problem...
 
laufdi said:
The modules are also different, maybe that's the problem...
Click to expand...
This can really be the root cause. Please check the data sheet of the RAM modules. Especially if the clock frequency or timing is different it is likeley that this is the root cause. I am not sure if swapping the modules would be some intermediate cure or some tweaking in the BIOS could help. As far as I know the RAM modules (of one bank) should be similar as a general rule.
 
The problems are new, the modules I have running much longer. But I will try to get a new pair of RAM.
I checked the modules in another machine with the same results.
 
If there is some kind of improvement that some processing runs faster it is more demanding for the hardware and everything is driven more close to the specs. So meeting the specs becomes more and more important because the headroom is reduced. At least this is my simple thinking.

I hope the new RAM will fix the issue :beer:!
 
Unfortunately it doesn't. I tested several pairs of RAM. All tested good in memtest. The hang of memtest86+ with SMP is apparently a bug so I switched to memtest.

I can reproduce the hangs when I do
# tar cvf /dev/null --one-file-system /somezfsdir
which hangs after a few seconds. When I then press Ctrl-C it will take 10-20 seconds to return.
When I switch to console and back to X, it will be stopped immediately.

I can do the same without problems on my FFS root dir including a 4 GB swap file.

So I suspect some zfs problems - ? The pool had no problems when I scrubbed it.
When I do something to make the disk reading slower (for example compress the output), the hang will not occur, so something is too fast for zfs - ?
The problem exists both on compressed and uncompressed zfs file systems.
 
From i5-530M or so to i7-620M, but I can't believe the type was the reason, it must have been either defective or the contacts bad.
 
This sounds more like a video driver thing. We used to see pauses and lags when people hand AEI disabled, but I'm pretty sure that AEI is ignored by the latest version of Xorg. Although maybe we do not have that version in FreeBSD yet.

Otherwise, it's possible that the i7-620M has a slightly different version of the GPU, one that is better supported by the driver.

This could also be an interaction between KMS and vt(4) or sc(4), depending on what is being used.
 
Yes it's externally built in :)

But the console doesn't use the Nvidia driver of course

Code: 
sc0: <System console> at flags 0x100 on isa0
sc0: VGA <16 virtual consoles, flags=0x300>
vga0: <Generic ISA VGA> at port 0x3c0-0x3df iomem 0xa0000-0xbffff on isa0
 
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