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As a part of its service function, a service usually polls some kind of source (e.g., an RX queue, a ring, an eventdev port, or a timer wheel) to retrieve one or more items of work. In low-load situations, the service framework reports a significant amount of cycles spent for all running services, despite the fact they have performed little or no actual work. The per-call cycle expenditure for an idle service (i.e., a service currently without pending jobs) is typically very low. Polling an empty ring or RX queue is inexpensive. However, since the service function call frequency on an idle or lightly loaded lcore is going to be very high indeed, the service function calls' cycles adds up to a significant amount. The only thing preventing the idle services' cycles counters to make up 100% of the available CPU cycles is the overhead of the service framework itself. If the RTE_SERVICE_ATTR_CYCLES or RTE_SERVICE_LCORE_ATTR_CYCLES are used to estimate service core load, the cores may look very busy when the system is mostly doing nothing useful at all. This patch allows for an idle service to indicate that no actual work was performed during a particular service function call (by returning -EAGAIN). In such cases the RTE_SERVICE_ATTR_CYCLES and RTE_SERVICE_LCORE_ATTR_CYCLES values are not incremented. The convention of returning -EAGAIN for idle services may in the future also be used to have the lcore enter a short sleep, or reduce its operating frequency, in case all services are currently idle. This change is backward-compatible. Signed-off-by: Mattias Rönnblom <mattias.ronnblom@ericsson.com> Acked-by: Morten Brørup <mb@smartsharesystems.com> Acked-by: Harry van Haaren <harry.van.haaren@intel.com>
DPDK is a set of libraries and drivers for fast packet processing. It supports many processor architectures and both FreeBSD and Linux. The DPDK uses the Open Source BSD-3-Clause license for the core libraries and drivers. The kernel components are GPL-2.0 licensed. Please check the doc directory for release notes, API documentation, and sample application information. For questions and usage discussions, subscribe to: users@dpdk.org Report bugs and issues to the development mailing list: dev@dpdk.org