RE: [RFC PATCH v1] net/i40e: put mempool cache out of API

[Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>]

<snip>

> Subject: RE: [RFC PATCH v1] net/i40e: put mempool cache out of API
> 
> > From: Feifei Wang [mailto:feifei.wang2@arm.com]
> > Sent: Monday, 13 June 2022 07.52
> >
> > Refer to "i40e_tx_free_bufs_avx512", this patch puts mempool cache out
> > of API to free buffers directly. There are two changes different with
> > previous version:
> > 1. change txep from "i40e_entry" to "i40e_vec_entry"
> > 2. put cache out of "mempool_bulk" API to copy buffers into it
> > directly
> >
> > Performance Test with l3fwd neon path:
> > 		with this patch
> > n1sdp:		no perforamnce change
> > amper-altra:	+4.0%
> >
> > Suggested-by: Konstantin Ananyev <konstantin.v.ananyev@yandex.ru>
> > Suggested-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
> > Signed-off-by: Feifei Wang <feifei.wang2@arm.com>
> > ---
> 
> Once again bypassing the mempool API and copy-pasting internal code from
> the mempool library to a PMD for performance optimization.
> 
> Certainly not happy about it, but it's already done elsewhere, and thus we
> should not deny it here...
> 
> Acked-by: Morten Brørup <mb@smartsharesystems.com>
This was done with the intention to understand the performance of the zero-copy mempool APIs that Konstantin suggested. Even though this patch does not have the zero-copy mempool APIs, it reflects the code/instructions of creating such as API. We are trying to show here that zero-copy mempool APIs will not provide equivalent performance of direct-rearm method.