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From: "Ruifeng Wang (Arm Technology China)" <Ruifeng.Wang@arm.com>
To: Bruce Richardson <bruce.richardson@intel.com>
Cc: "users@dpdk.org" <users@dpdk.org>,
	"Zhang, Qi Z" <qi.z.zhang@intel.com>,
	"Gavin Hu (Arm Technology China)" <Gavin.Hu@arm.com>,
	nd <nd@arm.com>,
	Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>
Subject: [dpdk-users] Query on IXGBE vPMD barrier after descriptors load
Date: Thu, 8 Aug 2019 10:21:55 +0000	[thread overview]
Message-ID: <AM0PR08MB398605008380413D7E9ACC4D9ED70@AM0PR08MB3986.eurprd08.prod.outlook.com> (raw)

Hi Bruce,

When reading IXGBE vPMD code, I have doubt on the barrier used.  Hope you can provide more info on this.

In function _recv_raw_pkts_vec, there is a compiler_barrier after load of descs[0]:
 https://code.dpdk.org/dpdk/latest/source/drivers/net/ixgbe/ixgbe_rxtx_vec_sse.c#L469<https://code.dpdk.org/dpdk/latest/source/drivers/net/ixgbe/ixgbe_rxtx_vec_sse.c>

Could you give some hint about what sequence it is ensuring?
Similar barrier for NEON vPMD on aarch64 platform impacts performance much.

Regards,
/Ruifeng




                 reply	other threads:[~2019-08-08 10:22 UTC|newest]

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