How to enable logging and where to find the logs

[David Marchand]

Hello,

On Thu, Feb 29, 2024 at 9:51 AM Sindhura Bandi
<sindhura.bandi at certesnetworks.com> wrote:
>
> I might be asking a basic question here. I'm facing some issues while bringing up a dpdk interface on ovs-dpdk on debian-12. Dpdk version is 22.11.1.
> Dpdk seems to fail to allocate a mempool, even though there seem to be enough free huge page memory available on the machine.
>

Well, this is more a OVS question than a DPDK one :-)
There are two things to configure here.


> I tried to enable dpdk debugs using the following command,
> ovs-vsctl set Open_vSwitch . other_config:dpdk-extra="--log-level=lib.mbuf:debug"

First, as you tried, you must ask DPDK to emit debug logs for the mbuf library.
The above configuration is fine.

Just a small note that since OVS 2.14 you can enable logs dynamically
without having to restart OVS / setting a dpdk-extra param in ovsdb.
For example, I have no dpdk-extra config.

# ovs-appctl dpdk/log-list | grep mbuf
id 16: lib.mbuf, level is info

# ovs-appctl dpdk/log-set lib.mbuf:debug

# ovs-appctl dpdk/log-list | grep mbuf
id 16: lib.mbuf, level is debug

>
> The command was accepted, but I don't see any logs from dpdk anywhere in my /var/log.

That is because OVS log framework applies a filter.

# ovs-appctl vlog/list | grep dpdk
dpdk               OFF        ERR       INFO
netdev_dpdk        OFF        ERR       INFO
netdev_offload_dpdk   OFF        ERR       INFO

The dpdk facility here is only logging ERR level messages to syslog,
and INFO level to the /var/log file.

You probably want to set:
# ovs-appctl vlog/set FILE:dpdk:dbg

# ovs-appctl vlog/list | grep dpdk
dpdk               OFF        ERR        DBG
netdev_dpdk        OFF        ERR       INFO
netdev_offload_dpdk   OFF        ERR       INFO


Hope that helps.

-- 
David Marchand