Thank you for the info. On Mon, Oct 23, 2023 at 8:19 PM Stephen Hemminger < step...@networkplumber.org> wrote:
> On Mon, 23 Oct 2023 18:32:48 +0300 > Pavel Vazharov <frea...@gmail.com> wrote: > > > Hi there, > > > > We've a DPDK based application from which we need to take packet dumps > from > > time to time when problems arise. We are planning to use librte_pdump > > functions and the dpdk-dumppcap tool. > > I've few questions in related to the pdump functionality which we want to > > use: > > - Is calling `rte_pdump_init` at the startup of the main application > > causing some overhead for the packet processing during its run if there > is > > no actual packet capturing enabled by the dpdk-dumppcap tool? I suppose > > there should be some check in place but is it something like a single > `if` > > condition on a boolean flag or something heavier? > > - Is it possible then to call `rte_pdump_init` during the runtime of the > > main application only when I know that I'm about to start the > dpdk-dumppcap > > tool? I mean, is it supported and safe to call `rte_pdump_init` and > > `rte_pdump_uninit` while the main application is running and processing > > packets or these functions are supposed to be called only at application > > startup and application stop. > > > > Thanks in advance, > > Pavel. > > Short answer: > The overhead only happens when the dump application is running. > > Long answer: > Running rte_pdump_init() tells adds an additional service to the > multi-process (primary/secondary) communication mechanism. > Secondary and primary process connect with each other over Unix > domain socket, and the services are handled by the multi-process > thread in the primary process. Adding a service does not interact > with fast path at all. > > The best way (as always) to discover this yourself is to read > the source code and follow along. >
