From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga05.intel.com (mga05.intel.com [192.55.52.43]) by dpdk.org (Postfix) with ESMTP id 76A125B38; Fri, 26 Oct 2018 10:47:06 +0200 (CEST) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 26 Oct 2018 01:47:05 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.54,427,1534834800"; d="scan'208";a="100866554" Received: from irsmsx110.ger.corp.intel.com ([163.33.3.25]) by fmsmga004.fm.intel.com with ESMTP; 26 Oct 2018 01:47:04 -0700 Received: from irsmsx106.ger.corp.intel.com ([169.254.8.45]) by irsmsx110.ger.corp.intel.com ([169.254.15.182]) with mapi id 14.03.0319.002; Fri, 26 Oct 2018 09:47:03 +0100 From: "Ananyev, Konstantin" To: "Xing, Beilei" , "Zhang, Qi Z" CC: "dev@dpdk.org" , "stable@dpdk.org" Thread-Topic: [dpdk-dev] [PATCH v2] net/i40e: fix Rx instability with vector mode Thread-Index: AQHUbPW01xh9dBDPH0CqhG+tCUgXb6UxMs8A Date: Fri, 26 Oct 2018 08:47:02 +0000 Message-ID: <2601191342CEEE43887BDE71AB9772580102FED12C@IRSMSX106.ger.corp.intel.com> References: <1540453252-128654-1-git-send-email-beilei.xing@intel.com> <1540535607-115720-1-git-send-email-beilei.xing@intel.com> In-Reply-To: <1540535607-115720-1-git-send-email-beilei.xing@intel.com> Accept-Language: en-IE, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-titus-metadata-40: eyJDYXRlZ29yeUxhYmVscyI6IiIsIk1ldGFkYXRhIjp7Im5zIjoiaHR0cDpcL1wvd3d3LnRpdHVzLmNvbVwvbnNcL0ludGVsMyIsImlkIjoiYjQxNzMwYWItZGViNS00NmVmLWI2ODYtNjMyODFlN2JiYzg0IiwicHJvcHMiOlt7Im4iOiJDVFBDbGFzc2lmaWNhdGlvbiIsInZhbHMiOlt7InZhbHVlIjoiQ1RQX05UIn1dfV19LCJTdWJqZWN0TGFiZWxzIjpbXSwiVE1DVmVyc2lvbiI6IjE3LjEwLjE4MDQuNDkiLCJUcnVzdGVkTGFiZWxIYXNoIjoiY2lXak9FdWhER0Q5dm0yXC9LMHRjQnhBcnAyYzBCNHBBQmk2ZHZPXC8xT3NrUDFTZVNTc3lmQTgzSkwzSFRVZlY5In0= x-ctpclassification: CTP_NT dlp-product: dlpe-windows dlp-version: 11.0.400.15 dlp-reaction: no-action x-originating-ip: [163.33.239.180] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Subject: Re: [dpdk-dev] [PATCH v2] net/i40e: fix Rx instability with vector mode X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 26 Oct 2018 08:47:07 -0000 Hi, >=20 > Previously, there is instability during vector Rx if descriptor > number is not power of 2, e.g. process hang and some Rx packets > are unexpectedly empty. That's because vector Rx mode assumes Rx > descriptor number is power of 2 when doing bit mask. > This patch allows vector mode only when the number of Rx descriptor > is power of 2. >=20 > Fixes: 8e109464c022 ("i40e: allow vector Rx and Tx usage") > Fixes: a3c83a2527e1 ("net/i40e: enable runtime queue setup") > Cc: stable@dpdk.org >=20 > Signed-off-by: Beilei Xing > --- >=20 > v2 changes: > - rx_vec_allowed is global configuration, avoid overwrite. >=20 > doc/guides/nics/i40e.rst | 7 +++++++ > drivers/net/i40e/i40e_rxtx.c | 13 ++++++++++++- > 2 files changed, 19 insertions(+), 1 deletion(-) >=20 > diff --git a/doc/guides/nics/i40e.rst b/doc/guides/nics/i40e.rst > index ab3928a..bfacbd1 100644 > --- a/doc/guides/nics/i40e.rst > +++ b/doc/guides/nics/i40e.rst > @@ -172,6 +172,13 @@ Runtime Config Options >=20 > -w 84:00.0,use-latest-supported-vec=3D1 >=20 > +Vector RX Pre-conditions > +~~~~~~~~~~~~~~~~~~~~~~~~ > +For Vector RX it is assumed that the number of descriptor rings will be = a power > +of 2. With this pre-condition, the ring pointer can easily scroll back t= o the > +head after hitting the tail without a conditional check. In addition Vec= tor RX > +can use this assumption to do a bit mask using ``ring_size - 1``. > + > Driver compilation and testing > ------------------------------ >=20 > diff --git a/drivers/net/i40e/i40e_rxtx.c b/drivers/net/i40e/i40e_rxtx.c > index a827456..f6dcca0 100644 > --- a/drivers/net/i40e/i40e_rxtx.c > +++ b/drivers/net/i40e/i40e_rxtx.c > @@ -1735,10 +1735,14 @@ i40e_dev_rx_queue_setup_runtime(struct rte_eth_de= v *dev, > * i40e_set_rx_function. > */ > ad->rx_bulk_alloc_allowed =3D true; > - ad->rx_vec_allowed =3D true; > dev->data->scattered_rx =3D use_scattered_rx; > if (use_def_burst_func) > ad->rx_bulk_alloc_allowed =3D false; > + /** > + * Vector mode is allowed only when number of Rx queue > + * descriptor is a power of 2. > + */ > + ad->rx_vec_allowed =3D !(rxq->nb_rx_desc & (rxq->nb_rx_desc - 1)); > i40e_set_rx_function(dev); > return 0; > } I think this is not complete - if it is not the first function, we have to= do: If (if (ad->rx_vec_allowed && (rxq->nb_rx_desc & (rxq->nb_rx_desc - 1) !=3D= 0) { PMD_DRV_LOG(ERR, ...); return -EINVAL; } BTW, here and below why not to use rte_is_power_of_2()?=20 Konstantin > @@ -1811,6 +1815,13 @@ i40e_dev_rx_queue_setup(struct rte_eth_dev *dev, > return -EINVAL; > } >=20 > + /** > + * Vector mode is allowed only when number of Rx queue > + * descriptor is a power of 2. > + */ > + if (ad->rx_vec_allowed) > + ad->rx_vec_allowed =3D !(nb_desc & (nb_desc - 1)); > + > /* Free memory if needed */ > if (dev->data->rx_queues[queue_idx]) { > i40e_dev_rx_queue_release(dev->data->rx_queues[queue_idx]);