Re: [dpdk-dev] [PATCH] cryptodev: fix restore crypto op alignment and layout

["Trahe, Fiona" <fiona.trahe@intel.com>]

> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Konstantin Ananyev
> Sent: Thursday, March 7, 2019 2:13 PM
> To: dev@dpdk.org
> Cc: akhil.goyal@nxp.com; umesh.kartha@caviumnetworks.com; De Lara Guarch, Pablo
> <pablo.de.lara.guarch@intel.com>; shally.verma@caviumnetworks.com; Ananyev, Konstantin
> <konstantin.ananyev@intel.com>
> Subject: [dpdk-dev] [PATCH] cryptodev: fix restore crypto op alignment and layout
> 
> in 18.08 new cache-aligned structure rte_crypto_asym_op was introduced.
> As it also was included into rte_crypto_op, it caused implicit change
> in rte_crypto_op layout and alignment: now rte_crypto_op is cahce-line
> aligned has a hole of 40/104 bytes between phys_addr and sym/asym op.
> It looks like unintended ABI breakage, plus such change can cause
> negative performance effects:
> - now status and sym[0].m_src lies on different cache-lines, so
>   post-process code would need extra cache-line read.
> - new alignment causes grow of the space requirements and cache-line
>   reads/updates for structures that contain rte_crypto_op inside.
> As there seems no actual need to have rte_crypto_asym_op cache-line
> aligned, and rte_crypto_asym_op is not intended to be used on it's own -
> the simplest fix is just to remove cache-line alignment for it.
> As the immediate positive effect: on IA ipsec-secgw performance increased
> by 5-10% (depending on the crypto-dev and algo used).
> My guess that on machines with 128B cache-line and lookaside-protocol
> capable crypto devices the impact will be even more noticeable.
> 
> Fixes: 26008aaed14c ("cryptodev: add asymmetric xform and op definitions")
> 
> Signed-off-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
Acked-by: Fiona Trahe <fiona.trahe@intel.com>