From: Stephen Hemminger <stephen@networkplumber.org>
To: Shahaf Shuler <shahafs@mellanox.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>,
Thomas Monjalon <thomas@monjalon.net>,
"olivier.matz@6wind.com" <olivier.matz@6wind.com>,
"wwasko@nvidia.com" <wwasko@nvidia.com>,
"spotluri@nvidia.com" <spotluri@nvidia.com>,
Asaf Penso <asafp@mellanox.com>,
Slava Ovsiienko <viacheslavo@mellanox.com>
Subject: Re: [dpdk-dev] [RFC PATCH 20.02] mbuf: hint PMD not to inline packet
Date: Thu, 17 Oct 2019 08:14:44 -0700 [thread overview]
Message-ID: <20191017081444.7f91b680@hermes.lan> (raw)
In-Reply-To: <20191017072723.36509-1-shahafs@mellanox.com>
On Thu, 17 Oct 2019 07:27:34 +0000
Shahaf Shuler <shahafs@mellanox.com> wrote:
> Some PMDs inline the mbuf data buffer directly to device. This is in
> order to save the overhead of the PCI headers involved when the device
> DMA read the buffer pointer. For some devices it is essential in order
> to reach the pick BW.
>
> However, there are cases where such inlining is in-efficient. For example
> when the data buffer resides on other device memory (like GPU or storage
> device). attempt to inline such buffer will result in high PCI overhead
> for reading and copying the data from the remote device.
>
> To support a mixed traffic pattern (some buffers from local DRAM, some
> buffers from other devices) with high BW, a hint flag is introduced in
> the mbuf.
> Application will hint the PMD whether or not it should try to inline the
> given mbuf data buffer. PMD should do best effort to act upon this
> request.
>
> Signed-off-by: Shahaf Shuler <shahafs@mellanox.com>
This kind of optimization is hard, and pushing the problem to the application
to decide seems like the wrong step. Can the driver just infer this
already because some mbuf's are external?
next prev parent reply other threads:[~2019-10-17 15:14 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-17 7:27 Shahaf Shuler
2019-10-17 8:16 ` Jerin Jacob
2019-10-17 10:59 ` Shahaf Shuler
2019-10-17 17:18 ` Jerin Jacob
2019-10-22 6:26 ` Shahaf Shuler
2019-10-22 15:17 ` Jerin Jacob
2019-10-23 11:24 ` Shahaf Shuler
2019-10-25 11:17 ` Jerin Jacob
2019-10-17 15:14 ` Stephen Hemminger [this message]
2019-10-22 6:29 ` Shahaf Shuler
2019-12-11 17:01 ` [dpdk-dev] [RFC v2] mlx5/net: " Viacheslav Ovsiienko
2019-12-27 8:59 ` Olivier Matz
2020-01-14 7:57 ` [dpdk-dev] [PATCH] net/mlx5: update Tx datapath to support no inline hint Viacheslav Ovsiienko
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