From: Wathsala Wathawana Vithanage <wathsala.vithanage@arm.com>
To: Stephen Hemminger <stephen@networkplumber.org>
Cc: "dev@dpdk.org" <dev@dpdk.org>, nd <nd@arm.com>, nd <nd@arm.com>
Subject: RE: [RFC v3 0/2] An API for Stashing Packets into CPU caches
Date: Tue, 22 Oct 2024 18:37:09 +0000 [thread overview]
Message-ID: <PAWPR08MB8909450AEE3CCAF6F59514A89F4C2@PAWPR08MB8909.eurprd08.prod.outlook.com> (raw)
In-Reply-To: <20241021181251.6f9f69b6@hermes.local>
Hi Stephen,
> There is a fundamental conflict with the increasing growth of "nerd knobs"
> like this in the DPDK. Users already have problems understanding DPDK and
> adding more complexity does not help.
>
> So any new feature like this should be:
> 1. Just work right without any configuration. It can't suck by default.
>
By default, this feature is disabled. It can be only enabled by calling the following
at the queue setup time.
rte_eth_dev_stashing_rx_config_set
rte_eth_dev_stashing_tx_config_set
It's unlikely for someone not familiar with TPH to call these functions.
The performance for them should be as good as without this feature.
> 2. The API's should be used in the drivers and core, not exposed up
> to the application. Most of the hot data structures are in the
> drivers now.
>
PMDs don't know which CPU and cache level to use with TPH.
That information needs to be conveyed to the PMD, for it to work.
Please suggest alternatives.
> 3. Fit into existing API models. Like rte_prefetch().
>
PCIe TPH is a hint from a PCIe device to the system interconnect
to push data into CPU caches. I cannot think of an existing API
that matches the semantics of TPH.
rte_prefetch() is a hint to the CPU from the application, something
totally different.
> Is the goal of DPDK enabling high speed applications, or enabling vendor
> benchmarks?
This is a vendor agnostic feature from the PCI-SIG implemented by almost
every hardware vendor in their NICs and SoCs.
FYI: Kernel patch - https://patchwork.kernel.org/project/linux-pci/patch/20240927215653.1552411-2-wei.huang2@amd.com/
next prev parent reply other threads:[~2024-10-22 18:37 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-15 22:11 [RFC v2] ethdev: an API for cache stashing hints Wathsala Vithanage
2024-07-17 2:27 ` Stephen Hemminger
2024-07-18 18:48 ` Wathsala Wathawana Vithanage
2024-07-20 3:05 ` Honnappa Nagarahalli
2024-07-17 10:32 ` Konstantin Ananyev
2024-07-22 11:18 ` Ferruh Yigit
2024-07-26 20:01 ` Wathsala Wathawana Vithanage
2024-09-22 21:43 ` Ferruh Yigit
2024-10-04 17:52 ` Stephen Hemminger
2024-10-04 18:46 ` Wathsala Wathawana Vithanage
2024-10-21 1:52 ` [RFC v3 0/2] An API for Stashing Packets into CPU caches Wathsala Vithanage
2024-10-21 1:52 ` [RFC v3 1/2] pci: introduce the PCIe TLP Processing Hints API Wathsala Vithanage
2024-10-21 1:52 ` [RFC v3 2/2] ethdev: introduce the cache stashing hints API Wathsala Vithanage
2024-10-21 7:36 ` Morten Brørup
2024-10-21 7:35 ` [RFC v3 0/2] An API for Stashing Packets into CPU caches Chenbo Xia
2024-10-21 12:01 ` Wathsala Wathawana Vithanage
2024-10-22 1:12 ` Stephen Hemminger
2024-10-22 18:37 ` Wathsala Wathawana Vithanage [this message]
2024-10-22 21:23 ` Stephen Hemminger
2024-10-23 17:59 ` [RFC v2] ethdev: an API for cache stashing hints Mattias Rönnblom
2024-10-23 20:18 ` Stephen Hemminger
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