Re: [dpdk-dev] [PATCH RFC v1 0/7] relax barriers for ENA PMD and small fixes

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 3/16/2020 9:34 AM, Chauskin, Igor wrote:
> Hi Gavin,
> 
> Thank you for the contribution.
> Please do not merge these changes (patches 0..7) till we (the ENA team) properly review and ack/nack.

Hi Igor,

Is there any progress on reviewing the set?

Thanks,
ferruh

> These changes can potentially provide performance improvement, yet we need to ensure they are applicable for all possible scenarios. Specifically, the behavior on x86 platforms is likely to be different.
> What testing have you done for these patches? Was x86 tested?
> 
> Thanks,
> Igor
> 
> -----Original Message-----
> From: Gavin Hu <gavin.hu@arm.com> 
> Sent: Friday, March 13, 2020 11:18 AM
> To: dev@dpdk.org
> Cc: nd@arm.com; david.marchand@redhat.com; thomas@monjalon.net; mk@semihalf.com; Tzalik, Guy <gtzalik@amazon.com>; Schmeilin, Evgeny <evgenys@amazon.com>; Chauskin, Igor <igorch@amazon.com>; mw@semihalf.com; Honnappa.Nagarahalli@arm.com; ruifeng.wang@arm.com; phil.yang@arm.com; joyce.kong@arm.com
> Subject: [EXTERNAL][PATCH RFC v1 0/7] relax barriers for ENA PMD and small fixes
> 
> CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you can confirm the sender and know the content is safe.
> 
> 
> 
> To ensure the stores to the host memory are observed by NIC HW before a door bell ring to the NIC HW and the HW starts actions, for example, doing DMA, a barrier is required on weak memory ordering platforms, like aarch64.
> 
> However, unnecessarily too strong barriers like 'dsb' on aarch64 will dampen performance.
> 
> In a typical doorbell use case, as NIC and CPU are in the outer sharable domain, a lighter weight 'dmb osh' barrier is sufficient.
> 
> The patch set relaxes the barriers in similar places and include one more patch for statistics logging with relaxed ordering and the other patch removing duplicate memset.
> 
> Note this set is submitted for RFC as we don't have physical ENA NICs in the lab and the patch set was not verified nor benchmarked.
> 
> Gavin Hu (7):
>   net/ena: remove duplicate barrier
>   net/ena: relax the barrier for doorbell ring
>   net/ena: relax the rmb for DMA
>   net/ena: relax barrier for completion queue update
>   net/ena: relax the barrier for bounce buffer
>   net/ena: use c11 atomic for statistics
>   net/ena: remove duplicate memset
> 
>  drivers/net/ena/base/ena_eth_com.c   |  2 +-
>  drivers/net/ena/base/ena_eth_com.h   |  6 ++--
>  drivers/net/ena/base/ena_plat_dpdk.h |  2 +-
>  drivers/net/ena/ena_ethdev.c         | 46 +++++++++++++++++-----------
>  drivers/net/ena/ena_ethdev.h         |  8 ++---
>  5 files changed, 38 insertions(+), 26 deletions(-)
> 
> --
> 2.17.1
>