From: "Morten Brørup" <mb@smartsharesystems.com>
To: "Bruce Richardson" <bruce.richardson@intel.com>,
"Jerin Jacob" <jerinjacobk@gmail.com>
Cc: "fengchengwen" <fengchengwen@huawei.com>,
"Thomas Monjalon" <thomas@monjalon.net>,
"Ferruh Yigit" <ferruh.yigit@intel.com>,
"dpdk-dev" <dev@dpdk.org>, "Nipun Gupta" <nipun.gupta@nxp.com>,
"Hemant Agrawal" <hemant.agrawal@nxp.com>,
"Maxime Coquelin" <maxime.coquelin@redhat.com>,
"Honnappa Nagarahalli" <honnappa.nagarahalli@arm.com>,
"Jerin Jacob" <jerinj@marvell.com>,
"David Marchand" <david.marchand@redhat.com>,
"Satananda Burla" <sburla@marvell.com>,
"Prasun Kapoor" <pkapoor@marvell.com>
Subject: Re: [dpdk-dev] [RFC PATCH] dmadev: introduce DMA device library
Date: Wed, 23 Jun 2021 12:10:02 +0200 [thread overview]
Message-ID: <98CBD80474FA8B44BF855DF32C47DC35C61883@smartserver.smartshare.dk> (raw)
In-Reply-To: <YNMBv31unTE4B1E/@bricha3-MOBL.ger.corp.intel.com>
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Bruce Richardson
> Sent: Wednesday, 23 June 2021 11.41
>
> [Also, you are not likely to want to offload a small
> copy, are you?]
Maybe. I would consider it for two reasons:
1. To avoid CPU cache pollution. E.g. copy packet data (or part of it) to memory that is not going to be used any time soon, such as a packet capture buffer.
When a packet has been DPI analyzed at ingress and put in a QoS queue for holding, the packet data will be cold at the time of egress. If such a packet is to be captured at egress, the CPU is not going to touch the data in the original packet anymore (only the TX NIC will). And if the copy of the packet is queued to be processed by a "capture storage readout" pipeline stage, the CPU core that copied the packet will not touch the copy either (only the CPU core in the "capture storage readout" pipeline stage will; but that may be minutes or hours later).
2. To simplify code by using the same method, regardless of size.
Although it might be more efficient copying 64 B packets using CPU instructions and 1518 B packets using DMA, writing code that only uses one of the methods might simplify things.
-Morten
next prev parent reply other threads:[~2021-06-23 10:10 UTC|newest]
Thread overview: 79+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-15 13:22 Chengwen Feng
2021-06-15 16:38 ` Bruce Richardson
2021-06-16 7:09 ` Morten Brørup
2021-06-16 10:17 ` fengchengwen
2021-06-16 12:09 ` Morten Brørup
2021-06-16 13:06 ` Bruce Richardson
2021-06-16 14:37 ` Jerin Jacob
2021-06-17 9:15 ` Bruce Richardson
2021-06-18 5:52 ` Jerin Jacob
2021-06-18 9:41 ` fengchengwen
2021-06-22 17:25 ` Jerin Jacob
2021-06-23 3:30 ` fengchengwen
2021-06-23 7:21 ` Jerin Jacob
2021-06-23 9:37 ` Bruce Richardson
2021-06-23 11:40 ` Jerin Jacob
2021-06-23 14:19 ` Bruce Richardson
2021-06-24 6:49 ` Jerin Jacob
2021-06-23 9:41 ` Bruce Richardson
2021-06-23 10:10 ` Morten Brørup [this message]
2021-06-23 11:46 ` Jerin Jacob
2021-06-23 14:22 ` Bruce Richardson
2021-06-18 9:55 ` Bruce Richardson
2021-06-22 17:31 ` Jerin Jacob
2021-06-22 19:17 ` Bruce Richardson
2021-06-23 7:00 ` Jerin Jacob
2021-06-16 9:41 ` fengchengwen
2021-06-16 17:31 ` Bruce Richardson
2021-06-16 18:08 ` Jerin Jacob
2021-06-16 19:13 ` Bruce Richardson
2021-06-17 7:42 ` Jerin Jacob
2021-06-17 8:00 ` Bruce Richardson
2021-06-18 5:16 ` Jerin Jacob
2021-06-18 10:03 ` Bruce Richardson
2021-06-22 17:36 ` Jerin Jacob
2021-06-17 9:48 ` fengchengwen
2021-06-17 11:02 ` Bruce Richardson
2021-06-17 14:18 ` Bruce Richardson
2021-06-18 8:52 ` fengchengwen
2021-06-18 9:30 ` Bruce Richardson
2021-06-22 17:51 ` Jerin Jacob
2021-06-23 3:50 ` fengchengwen
2021-06-23 11:00 ` Jerin Jacob
2021-06-23 14:56 ` Bruce Richardson
2021-06-24 12:19 ` fengchengwen
2021-06-26 3:59 ` [dpdk-dev] dmadev discussion summary fengchengwen
2021-06-28 10:00 ` Bruce Richardson
2021-06-28 11:14 ` Ananyev, Konstantin
2021-06-28 12:53 ` Bruce Richardson
2021-07-02 13:31 ` fengchengwen
2021-07-01 15:01 ` Jerin Jacob
2021-07-01 16:33 ` Bruce Richardson
2021-07-02 7:39 ` Morten Brørup
2021-07-02 10:05 ` Bruce Richardson
2021-07-02 13:45 ` fengchengwen
2021-07-02 14:57 ` Morten Brørup
2021-07-03 0:32 ` fengchengwen
2021-07-03 8:53 ` Morten Brørup
2021-07-03 9:08 ` Jerin Jacob
2021-07-03 12:24 ` Morten Brørup
2021-07-04 7:43 ` Jerin Jacob
2021-07-05 10:28 ` Morten Brørup
2021-07-06 7:11 ` fengchengwen
2021-07-03 9:45 ` fengchengwen
2021-07-03 12:00 ` Morten Brørup
2021-07-04 7:34 ` Jerin Jacob
2021-07-02 7:07 ` Liang Ma
2021-07-02 13:59 ` fengchengwen
2021-06-24 7:03 ` [dpdk-dev] [RFC PATCH] dmadev: introduce DMA device library Jerin Jacob
2021-06-24 7:59 ` Morten Brørup
2021-06-24 8:05 ` Jerin Jacob
2021-06-23 5:34 ` Hu, Jiayu
2021-06-23 11:07 ` Jerin Jacob
2021-06-16 2:17 ` Wang, Haiyue
2021-06-16 8:04 ` Bruce Richardson
2021-06-16 8:16 ` Wang, Haiyue
2021-06-16 12:14 ` David Marchand
2021-06-16 13:11 ` Bruce Richardson
2021-06-16 16:48 ` Honnappa Nagarahalli
2021-06-16 19:10 ` Bruce Richardson
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