Developers

@jemerson93 It’s very interesting we see this or similar issues on many different platforms - hardware as well as virtualized environments. There does not seem to be a general answer and those kind of things have been around for years - when you search for rcu_sched you find tons of messages in kernel related mailing lists and forums.

But still this got more and more lately in the FOG forums as well and we are not sure why yet. But moving back to 4.15.2 kernel helped most of the people. We have seen issues with the newer init files not being compatible with this kernel and so I might ask you to manually download those more compatible inits (64 bit and 32bit). Rename/backup the ones you have in /var/www/html/fog/service/ipxe and put those in place (names init.xz and init_32.xz). Then downgrade to the 4.15.2 kernel and see if you still get the ugly error you had before when trying to downgrade the kernel.

If that doesn’t work then I expect this particular issue to be a problem with Hyper-V and Linux kernel option PAGE_TABLE_ISOLATION - Meltdown patch (ref). But would be kind of strange as we have this option enabled in all later kernel version. Nevertheless you can try going back to even older versions of kernel and init. Find those used in FOG 1.5.0 here (kernel 4.13.4).

Beside that I have tried to find current information specific to Hyper-V. Not much I could find, really. https://access.redhat.com/solutions/3743631 (anyone who’s access to RedHat stuff? @Wayne-Workman?)

@totoro Ok, here we go, I started to build all the kernel versions between 4.18.3 and 4.19.1 to see if can pinpoint it to a specific kernel version introducing the issue. Find the kernels here: https://fogproject.org/kernels/r8169/ (only 64 bit as your machines seems to be that arch)

Please start testing upwards starting from 4.18.4. Download the kernels manually, put in /var/www/html/fog/service/ipxe/ and then set Host Kernel in the host settings of your test machine. Schedule a task for that machine, boot it up and see if it is able to get an IP from your DHCP. If it fails on 4.18.4 already, then please go back to 4.18.3 again and make sure it works with that. Just to make sure it’s not something else causing the issue at that point.

Be aware, this is only the very first stage. To be able to send in a proper bug report to the kernel developers we’ll probably need to test different commits between the official kernel releases as well. Stay tuned!

@jemerson93 I meant the stall from the initial post.

@TheDiskDrive Do you use any FOG plugins like “location” or “site”?

@Seydoo said in No DHCP after PxE Menu:

I plug a computer on the switch which directly connected to the physical server and… it works
so now… I have to find where the issue is

Spanning tree (talk to your network guys and ask them to set the ports to “port fast”) or some kind of EEE (ethernet energy saving) stuff. Just my guess on what could be the issue.

Another tool to monitoting apache activity is apachetop. This tool gives you more info than modStatus

@Fernando-Gietz said in Performance Monitoring tools:

Yes, I used it sometimes but only to see the activity in one moment, you can’t see a history of the activity. I would like to see the activity of apache in the last 4 hours, for example.

That’s definitely a good point! Just found a tools that collects and aggregates the stats (https://docs.netdata.cloud/collectors/charts.d.plugin/apache/ and https://www.monitorix.org/). I am sure there are other tools doing just the same as well. For example if you use Cacti (https://forums.cacti.net/about25227.html).

@Sebastian-Roth Yes, I used it sometimes but only to see the activity in one moment, you can’t see a history of the activity. I would like to see the activity of apache in the last 4 hours, for example.

@Fernando-Gietz Have you heard of the mod_status module yet? Find some information here: https://www.datadoghq.com/blog/collect-apache-performance-metrics/ (don’t get too fance about the colorful picture -> this is not in current Apache 2.4 but will be in later releases)

We use Nagios to monitoring the server status but not use any plugin to see the activity of MySQL or Apache. Do you use any plugin to monitoring these services?