Add limitations to use of the dpdk-test-crypto-perf tool for hardware accelerator measurements
Signed-off-by: Fiona Trahe <fiona.tr...@intel.com> --- doc/guides/tools/cryptoperf.rst | 16 ++++++++++++++++ 1 files changed, 16 insertions(+), 0 deletions(-) diff --git a/doc/guides/tools/cryptoperf.rst b/doc/guides/tools/cryptoperf.rst index 6832312..af58e78 100644 --- a/doc/guides/tools/cryptoperf.rst +++ b/doc/guides/tools/cryptoperf.rst @@ -41,6 +41,22 @@ chain mode have to be specified in the command line as application parameters. These parameters are checked using device capabilities structure. +Limitations: +------------ +On hardware devices the cycle-count doesn't always represent the actual offload +cost. The cycle-count only represents the offload cost when the hardware +accelerator is not fully loaded, when loaded the cpu cycles freed up by the +offload are still consumed by the test tool and included in the cycle-count. +These cycles are consumed by retries and inefficient API calls enqueuing and +dequeuing smaller bursts than specified by the cmdline parameter. This results +in a larger cycle-count measurement and should not be interpreted as an offload +cost measurement. + +On hardware devices the throughput measurement is not necessarily the maximum +possible for the device, e.g. it may be necessary to use multiple cores to keep +the hardware accelerator fully loaded and so measure maximum throughput. + + Compiling the Application ------------------------- -- 1.7.0.7
