[dpdk-dev] [PATCH] app/crypto-perf: add minimise-offload-cost flag

[Trahe, Fiona]

> -----Original Message-----
> From: Trahe, Fiona
> Sent: Tuesday, May 9, 2017 5:14 PM
> To: dev at dpdk.org; Mrozowicz, SlawomirX <slawomirx.mrozowicz at intel.com>
> Cc: Doherty, Declan <declan.doherty at intel.com>; Griffin, John <john.griffin at intel.com>; De Lara Guarch,
> Pablo <pablo.de.lara.guarch at intel.com>; Trahe, Fiona <fiona.trahe at intel.com>
> Subject: [PATCH] app/crypto-perf: add minimise-offload-cost flag
> 
> The throughput test enqueues and dequeues bursts of operations
> to the device. For software devices the full burst size will
> usually be successfully en/dequeued, on hardware devices
> however the CPU can call the API more frequently than necessary,
> as it has nothing else to do.
> Minimum offload cost is achieved when the specified
> burst_size is en/dequeued. So rather than
> wasting CPU cycles continually retrying, with a
> fraction of the burst being en/dequeued each time,
> fewer CPU cycles are used by backing off until a full
> burst can be enqueued.
> 
> This patch adds a --minimise-offload-cost flag.
> When set the test backs off until full bursts are
> en/dequeued and counts the cycles while waiting.
> These cycles represent cycles saved by
> offloading, which in a real application are
> available for other work. Hence these cycles are
> deducted from the total cycle-count to show the
> minimum offload-cost which can be acheived.
> 
> Signed-off-by: Fiona Trahe <fiona.trahe at intel.com>
Self-nack
As we're intending to push a better way to measure HW offload cost in next release.