linux-kernel - Re: [PATCH V3 00/10] PCIe TPH and cache direct injection support

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Message-ID: <04af4272-015f-461a-84f9-c6afcd30bf82@amd.com>
Date: Mon, 22 Jul 2024 10:38:19 -0500
From: Wei Huang <wei.huang2@....com>
To: David Wei <dw@...idwei.uk>, linux-pci@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
 netdev@...r.kernel.org
Cc: Jonathan.Cameron@...wei.com, helgaas@...nel.org, corbet@....net,
 davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
 pabeni@...hat.com, alex.williamson@...hat.com, gospo@...adcom.com,
 michael.chan@...adcom.com, ajit.khaparde@...adcom.com,
 somnath.kotur@...adcom.com, andrew.gospodarek@...adcom.com,
 manoj.panicker2@....com, Eric.VanTassell@....com, vadim.fedorenko@...ux.dev,
 horms@...nel.org, bagasdotme@...il.com, bhelgaas@...gle.com
Subject: Re: [PATCH V3 00/10] PCIe TPH and cache direct injection support



On 7/20/24 14:25, David Wei wrote:
> On 2024-07-17 13:55, Wei Huang wrote:
>> Hi All,
>>
>> TPH (TLP Processing Hints) is a PCIe feature that allows endpoint devices to
>> provide optimization hints for requests that target memory space. These hints,
>> in a format called steering tag (ST), are provided in the requester's TLP
>> headers and allow the system hardware, including the Root Complex, to
>> optimize the utilization of platform resources for the requests.
>>
>> Upcoming AMD hardware implement a new Cache Injection feature that leverages
>> TPH. Cache Injection allows PCIe endpoints to inject I/O Coherent DMA writes
>> directly into an L2 within the CCX (core complex) closest to the CPU core that
>> will consume it. This technology is aimed at applications requiring high
>> performance and low latency, such as networking and storage applications.
> 
> This sounds very exciting Wei and it's good to see bnxt support. When
> you say 'upcoming AMD hardware' are you able to share exactly which? I
> would like to try this out.

I can't specify which server platforms yet. But you can find this
feature in either BIOS options or decode it from ACPI DSDT table (search
UUID e5c937d0-3553-4d7a-9117-ea4d19c3434d, Func 0x0F).