Embedded Linux Conference Europe

This presentation describes how hardware instrumentation IPs embedded into the OMAP4 interconnect were used in order to debug and improve the performance of the system DMA. This system DMA was involved into a data encryption pipeline which was under performing in comparison to theoretical expectations prior to this analysis. Usual tools were first used: Tracing, Systemtap. However in such a use case where several hardware accelerators are first configured and then used in the data path in a data pipe lining fashion, such tools could not help to pinpoint the exact performance gap. In order to get visibility into what was happening, hardware tools called OCP watchpoint were activated and used. They allowed to identify issues in the system DMA configuration and to quantify the latency budget among the different contributors.