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From: Jerin Jacob <jerinjacobk@gmail.com>
To: Gavin Hu <gavin.hu@arm.com>
Cc: dpdk-dev <dev@dpdk.org>, nd <nd@arm.com>,
	David Marchand <david.marchand@redhat.com>,
	 Thomas Monjalon <thomas@monjalon.net>,
	Raslan Darawsheh <rasland@mellanox.com>,
	Maxime Coquelin <maxime.coquelin@redhat.com>,
	Tiwei Bie <tiwei.bie@intel.com>,
	 Matan Azrad <matan@mellanox.com>,
	Shahaf Shuler <shahafs@mellanox.com>,
	 Slava Ovsiienko <viacheslavo@mellanox.com>,
	Andrew Rybchenko <arybchenko@solarflare.com>,
	 Stephen Hemminger <stephen@networkplumber.org>,
	Hemant Agrawal <hemant.agrawal@nxp.com>,
	 Jerin Jacob <jerinj@marvell.com>,
	Pavan Nikhilesh <pbhagavatula@marvell.com>,
	 Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>,
	 "Ruifeng Wang (Arm Technology China)" <ruifeng.wang@arm.com>,
	Phil Yang <phil.yang@arm.com>,  Joyce Kong <joyce.kong@arm.com>,
	Steve Capper <steve.capper@arm.com>
Subject: Re: [dpdk-dev] [PATCH v3] net/i40e: relaxed barrier in the tx fastpath
Date: Sat, 15 Feb 2020 13:55:15 +0530
Message-ID: <CALBAE1MRY-7116L3puV6tE4Yxu+tQV_z3f2Dduf8zkvLqXRb4g@mail.gmail.com> (raw)
In-Reply-To: <20200208134808.212027-1-gavin.hu@arm.com>

On Sat, Feb 8, 2020 at 7:22 PM Gavin Hu <gavin.hu@arm.com> wrote:
>
> To keep ordering of mixed accesses, rte_cio is sufficient.
> The rte_io barrier is overkill.[1]
>
> [1] http://inbox.dpdk.org/dev/CALBAE1M-ezVWCjqCZDBw+MMDEC4O9
> qf0Kpn89EMdGDajepKoZQ@mail.gmail.com
>
> Signed-off-by: Gavin Hu <gavin.hu@arm.com>
> ---
> V3:
> - optimize the barriers in the fast path only, leave as it is for the
>   barriers in the slow path and control path <jerin>
> - drop the virtio patches from the list as they are in the control path
> - it makes more sense to relax the barrier in the fast path, at the PMD level.
>   relaxing the fundamental rte_io_x barriers APIs requires scrutinizations for
>   each PMDs which use the barriers directly or indirectly.
> V2:
> - remove virtio_pci_read/write64 APIs definitions, they are not needed and generate compiling errors like " error: unused function 'virtio_pci_write64' [-Werror,-Wunused-function]"
> - update the reference link to kernel source code
> ---
>  drivers/net/i40e/i40e_rxtx.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/i40e/i40e_rxtx.c b/drivers/net/i40e/i40e_rxtx.c
> index fd1ae80da..8c0f7cc67 100644
> --- a/drivers/net/i40e/i40e_rxtx.c
> +++ b/drivers/net/i40e/i40e_rxtx.c
> @@ -1248,7 +1248,8 @@ i40e_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
>                    (unsigned) txq->port_id, (unsigned) txq->queue_id,
>                    (unsigned) tx_id, (unsigned) nb_tx);
>
> -       I40E_PCI_REG_WRITE(txq->qtx_tail, tx_id);
> +       rte_cio_wmb();
> +       I40E_PCI_REG_WRITE_RELAXED(txq->qtx_tail, tx_id);

Looks good to me from the ARM64 perspective or in general.

Reviewed-by: Jerin Jacob <jerinj@marvell.com>





>         txq->tx_tail = tx_id;
>
>         return nb_tx;
> --
> 2.17.1
>

  parent reply index

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-22 15:27 [dpdk-dev] [PATCH v1 0/3] relax io barrier for aarch64 and use smp barriers for virtual pci memory Gavin Hu
2019-10-22 15:27 ` [dpdk-dev] [PATCH v1 1/3] eal/arm64: relax the io barrier for aarch64 Gavin Hu
2019-10-22 15:27 ` [dpdk-dev] [PATCH v1 2/3] net/virtio: virtual PCI requires smp barriers Gavin Hu
2019-10-22 15:27 ` [dpdk-dev] [PATCH v1 3/3] crypto/virtio: " Gavin Hu
2019-10-23  8:22 ` [dpdk-dev] [PATCH v1 0/3] relax io barrier for aarch64 and use smp barriers for virtual pci memory Maxime Coquelin
2019-11-07  1:13   ` Gavin Hu (Arm Technology China)
2019-12-20  3:09 ` [dpdk-dev] [PATCH v2 " Gavin Hu
2019-12-20  3:09 ` [dpdk-dev] [PATCH v2 1/3] eal/arm64: relax the io barrier for aarch64 Gavin Hu
2019-12-20  3:33   ` Jerin Jacob
2019-12-20  3:38     ` Jerin Jacob
2019-12-20  4:19       ` Gavin Hu
2019-12-20  4:34         ` Jerin Jacob
2019-12-20  6:32           ` Gavin Hu
2019-12-20  6:55             ` Jerin Jacob
2019-12-23  9:14               ` Gavin Hu
2019-12-23  9:19                 ` Jerin Jacob
2019-12-23 10:16                   ` Gavin Hu
2020-01-02  9:51                     ` Jerin Jacob
2020-01-03  6:30                       ` Gavin Hu
2020-01-03  7:34                         ` Jerin Jacob
2020-01-03  9:12                           ` Gavin Hu
2019-12-20  3:09 ` [dpdk-dev] [PATCH v2 2/3] net/virtio: virtual PCI requires smp barriers Gavin Hu
2019-12-20  8:17   ` Tiwei Bie
2019-12-20 10:19     ` Gavin Hu
2019-12-20  3:09 ` [dpdk-dev] [PATCH v2 3/3] crypto/virtio: " Gavin Hu
2020-02-08 13:48 ` [dpdk-dev] [PATCH v3] net/i40e: relaxed barrier in the tx fastpath Gavin Hu
2020-02-11  2:11   ` Ye Xiaolong
2020-02-12  6:02     ` Gavin Hu
2020-02-15  8:25   ` Jerin Jacob [this message]
2020-02-12  5:56 ` [dpdk-dev] [PATCH v4] " Gavin Hu
2020-02-15 15:16   ` Ye Xiaolong
2020-02-16  9:51     ` Thomas Monjalon
2020-02-16 16:38       ` Ye Xiaolong
2020-02-16 17:36         ` Thomas Monjalon

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