On 04/22/2018 09:17 PM, Frank Scheiner wrote:
Some switches support a half-duplex back pressure form of flow control.
I'll try that now. According to the documentation my switch can create
back-pressure as form of flow control.
Yesterday after I activated flow control on the switch, the 712/80 got
back after a while and finished the `apt list --upgradable` command with
output - in between the journald of systemd crashed and restarted.
Reissuing the same `apt [...]` command worked without problems. On the
switch's port summary I could now also recognize that the host that acts
as NFS server now got pause frames submitted by the switch - so the flow
control is working.
I then tried to install `joe` and when `update-alternatives` started it
again lost the connection to the NFS server. :-( It didn't recover from
that - at least not during the time I waited for it - so I powered the
712/80 down.
I thought maybe switching back to System V init might ease the load a
little bit for the 712/80, so I upgraded the file system with a c8000
(incl. newer patch level for the kernel) and removed systemd afterwards
(also from initramfs).
I then ran some benchmarks without any issues in between.
Today I still have the problems described in [1] when doing `apt install
[...]` or `apt remove [...]` but now the 712/80 recovered each time so
far after a while, so it looks like an improvement to me. Look at the
timings for `apt remove [...]`:
```
root@hp-712:~# time apt remove -y joe
[ 8794.150750] nfs: server 172.16.0.2 not responding, still trying
[...]
[ 8794.962227] nfs: server 172.16.0.2 not responding, still trying
[ 8795.074226] nfs: server 172.16.0.2 OK
[...]
[ 8797.271834] nfs: server 172.16.0.2 OK
[ 8802.242312] nfs: server 172.16.0.2 not responding, still trying
[...]
[ 9235.937478] nfs: server 172.16.0.2 OK
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be REMOVED:
joe
0 upgraded, 0 newly installed, 1 to remove and 0 not upgraded.
After this operation, 2,086 kB disk space will be freed.
(Reading database ... 41128 files and directories currently installed.)
Removing joe (4.6-1) ...
update-alternatives: using /usr/bin/jmacs to provide /usr/bin/editor
(editor) in auto mode
update-alternatives: using /usr/bin/jpico to provide /usr/bin/editor
(editor) in auto mode
update-alternatives: using /bin/nano to provide /usr/bin/editor (editor)
in auto mode
Processing triggers for mime-support (3.60) ...
[ 9357.992385] nfs: server 172.16.0.2 not responding, still trying
[...]
[10055.370493] nfs: server 172.16.0.2 not responding, still trying
[10055.709731] nfs: server 172.16.0.2 OK
[...]
[10057.212469] nfs: server 172.16.0.2 OK
real 22m0.853s
user 1m3.264s
sys 0m43.875s
```
...the `apt install -y joe` done beforehand took about 41 minutes. So
the 712/80 can recover from the described problems, but package
management should really be done from a more powerful machine, at least
when running diskless.
[1]: https://lists.debian.org/debian-hppa/2018/04/msg00007.html
Cheers,
Frank
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