After Yamagi brought this work to my attention and told me that it was possible to apply this patch to FreeBSD 12.0 I created this diff from the git repo. I applied the patch to FreeBSD 12.0 on a T470s. With this patch the cores clock independently, power consumption is reduced (especially with low to medium load) and peak performance improved.

I would just like to state that I'm neither the maintainer of s6-rc nor did the maintainer for s6-rc (moo@arthepsy.eu) set a maintainer approved flag for my patch in PR #232053.

In D17304#369051, @crest_bultmann.eu wrote:

I'm testing this patch against r338924 on the same EYPC 7551P 32core system used for testing against D17059.

I'm testing this patch against r338924 on the same EYPC 7551P 32core system used for testing against D17059.

I removed enough DIMMs to balance all four NUMA domains on my 32core EPYC system. Now each of the four domains contains a single 32GB DIMM for a total of 128GB. Under load (again multiple dd processes writing to ZFS) the system still swaps out complete processes (e.g. login shells running zpool iostat or top). If those processes exit and their parent shell was swapped out it can take over a minute until the shell is swapped back int although there are at least 3GB of free memory spread over all domains according to top.

In D17059#367066, @markj wrote:

In D17059#367064, @crest_bultmann.eu wrote:

In D17059#367059, @markj wrote:

In D17059#366975, @crest_bultmann.eu wrote:

I have to revise my statement. I tried an other torture test (six dd if=/dev/zero bs=1m of=/kkdata/benchmark/$RANDOM writing to an uncompressed dataset). The system is still writing at about 1GB/s with the patch, but trying to exit some tools (e.g. zpool, top) hangs. Here is the procstat -kka output:

procstat.hang2.txt451 KBDownload

I don't see any such processes in the procstat output. Did you try this test without "options NUMA"?

Did you look at the zsh processes as well? I observed no hangs without "options NUMA".

Yes, seems they're just waiting for children to report an exit status. I am wondering if the processes got swapped out. Could you provide "ps auxwwwH" output?

In D17059#367059, @markj wrote:

In D17059#366975, @crest_bultmann.eu wrote:

I have to revise my statement. I tried an other torture test (six dd if=/dev/zero bs=1m of=/kkdata/benchmark/$RANDOM writing to an uncompressed dataset). The system is still writing at about 1GB/s with the patch, but trying to exit some tools (e.g. zpool, top) hangs. Here is the procstat -kka output:

procstat.hang2.txt451 KBDownload

I don't see any such processes in the procstat output. Did you try this test without "options NUMA"?

I have to revise my statement. I tried an other torture test (six dd if=/dev/zero bs=1m of=/kkdata/benchmark/$RANDOM writing to an uncompressed dataset). The system is still writing at about 1GB/s with the patch, but trying to exit some tools (e.g. zpool, top) hangs. Here is the procstat -kka output:

In D17209#366880, @cem wrote:

This changes keg cursor advancement behavior slightly. I'm not sure that matters.

In D17059#366834, @markj wrote:

I think I see the problem. Could you test with the diff at D17209 applied?

In D17059#366775, @markj wrote:

In D17059#366774, @crest_bultmann.eu wrote:

In D17059#366732, @markj wrote:

In D17059#366566, @crest_bultmann.eu wrote:

This is the output from top -HSazo res when writes to ZFS stopped beeing processed on the system with a NUMA enabled kernel:

Thanks. Could you also grab "procstat -kka" output from the system in this state?

Here is the requested output from procstat -kka of a hanging system.

procstat.hang.txt454 KBDownload

Great, this helps. Finally, could I ask for output from "sysctl vm", again from the system in this state?

In D17059#366732, @markj wrote:

In D17059#366566, @crest_bultmann.eu wrote:

This is the output from top -HSazo res when writes to ZFS stopped beeing processed on the system with a NUMA enabled kernel:

Thanks. Could you also grab "procstat -kka" output from the system in this state?

This is the output from top -HSazo res when writes to ZFS stopped beeing processed on the system with a NUMA enabled kernel:

This time I triggered a panic via sysctl a few minutes after ZFS writes hung but before the kernel panic()ed on its own.

I gave up after >500 screenshots of the IPMI KVM output. I haven't yet found a working configuration for the Serial over LAN. I'm trying again with a dump device large enough to hold >200GB RAM.

Never mind. The ghosts in the machine read my post. The kernel just panic()ed again. I'm at the kernel debugger prompt in the IPMI KVM webinterface.

After copying 110TB between two pools with zfs send | mbuffer -m1g -s128k | zfs recv on a kernel without "options NUMA" I bootet a kernel with "options NUMA" build from revision 338698. ZFS writes still hang, but the system doesn't panic. The mbuffer output shows that the buffer remains 100% full when writes hang.

I attached a screenshot of the system console taken via IPMI

With the NUMA option enabled ZFS hangs after a few minutes of heavy write load causing the deadman switch to panic the kernel on a 32 core AMD EPCY 7551P. I can still write to the swap partitions on the same disks while writes to ZFS on an other partition hang.