On 11/10/2017 10:12 AM, Adrien Mazarguil wrote: > Since testpmd is a development tool not supposed to run in a production > environment, is there really a need for it to be patched to work around a > (temporary) Linux kernel bug?
>From the kernel side... not even... > If so, why is I/O the only forwarding mode impacted? > > If it's used in a production environment and such a fix can't wait, have > other workarounds been considered: > > - Replacing testpmd in I/O mode with a physical cable or switch? using proper options like: > - Using proper options on the kernel command line as described in [1], such > as isolcpus, rcu_nocbs, nohz_full? Guarantees you that a CPU is completely isolated. In the current state of the art, it is not possible to assume that a CPU can be fully isolated from OS housekeeping threads. For example, some kernel sub-systems rely on executing on every CPU, e.g., using kworkers, and they are not only tracing or debugging options. That case Marcelo showed is just a straightforward to use use-case. If a busy-loop-isolated task runs with rt priority, it will end up delaying such workers to run, making system to complain about hung tasks. -- Daniel
