From: Leon Romanovsky <leon@kernel.org>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: "Bjorn Helgaas" <bhelgaas@google.com>,
"Logan Gunthorpe" <logang@deltatee.com>,
"Jason Gunthorpe" <jgg@ziepe.ca>,
"Joerg Roedel (AMD)" <joro@8bytes.org>,
"Will Deacon" <will@kernel.org>,
"Robin Murphy" <robin.murphy@arm.com>,
"Christian König" <christian.koenig@amd.com>,
"Thomas Hellström" <thomas.hellstrom@linux.intel.com>,
linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-doc@vger.kernel.org, iommu@lists.linux.dev,
"Tushar Dave" <tdave@nvidia.com>,
linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org,
linaro-mm-sig@lists.linaro.org, linux-rdma@vger.kernel.org,
kvm@vger.kernel.org, "Chaitanya Kulkarni" <kch@nvidia.com>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Jens Axboe" <axboe@kernel.dk>,
"Alex Williamson" <alex@shazbot.org>,
"Ankit Agrawal" <ankita@nvidia.com>,
"Jonathan Corbet" <corbet@lwn.net>,
"Shuah Khan" <skhan@linuxfoundation.org>,
"Randy Dunlap" <rdunlap@infradead.org>,
"Sumit Semwal" <sumit.semwal@linaro.org>
Subject: Re: [PATCH v9 06/18] PCI/P2PDMA: Collect the path's ACS controls before deciding
Date: Wed, 7 Oct 2026 16:50:44 +0300 [thread overview]
Message-ID: <20261007135044.GG7822@unreal> (raw)
In-Reply-To: <20261006214858.GA717151@bhelgaas>
On Tue, Oct 06, 2026 at 04:48:58PM -0500, Bjorn Helgaas wrote:
> On Thu, Oct 01, 2026 at 02:55:14PM +0300, Leon Romanovsky wrote:
> > From: Leon Romanovsky <leonro@nvidia.com>
> >
> > calc_map_type_and_dist() reads each divergence port's ACS Control register
> > and folds the result into running counters as it goes. Any routing property
> > that depends on the kind of TLP being routed would have to be threaded
> > through that code, so there is nowhere to put one without reading the
> > registers again for each kind.
>
> What is the "one" that there's nowhere to put? I guess the routing
> property? So this is an optimization to avoid some config reads?
Right, cache the ACS bits, since we need to query them for both devices
whenever we calculate routing.
Thanks
next prev parent reply other threads:[~2026-10-07 13:50 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-01 11:55 [PATCH v9 00/18] PCI/P2PDMA: Route peer-to-peer DMA by TLP class Leon Romanovsky
2026-10-01 11:55 ` [PATCH v9 01/18] PCI/P2PDMA: Document the TLP attribute assumptions Leon Romanovsky
2026-10-01 11:55 ` [PATCH v9 02/18] PCI/P2PDMA: Derive routing from directional ACS controls Leon Romanovsky
2026-10-06 20:49 ` Bjorn Helgaas
2026-10-07 6:32 ` Leon Romanovsky
2026-10-01 11:55 ` [PATCH v9 03/18] PCI: Reject unreadable ACS controls in isolation checks Leon Romanovsky
2026-10-01 11:55 ` [PATCH v9 04/18] PCI/P2PDMA: Evaluate ACS controls at the path divergence Leon Romanovsky
2026-10-06 21:08 ` Bjorn Helgaas
2026-10-07 10:51 ` Leon Romanovsky
2026-10-01 11:55 ` [PATCH v9 05/18] PCI/P2PDMA: Document directional ACS routing Leon Romanovsky
2026-10-06 21:32 ` Bjorn Helgaas
2026-10-07 13:46 ` Leon Romanovsky
2026-10-01 11:55 ` [PATCH v9 06/18] PCI/P2PDMA: Collect the path's ACS controls before deciding Leon Romanovsky
2026-10-06 21:48 ` Bjorn Helgaas
2026-10-07 13:50 ` Leon Romanovsky [this message]
2026-10-01 11:55 ` [PATCH v9 07/18] PCI/P2PDMA: Answer routing per TLP class Leon Romanovsky
2026-10-01 11:55 ` [PATCH v9 08/18] PCI/P2PDMA: Route Relaxed Ordering Completions directly Leon Romanovsky
2026-10-06 22:21 ` Bjorn Helgaas
2026-10-01 11:55 ` [PATCH v9 09/18] PCI/P2PDMA: Reject Translated Requests blocked by Translation Blocking Leon Romanovsky
2026-10-01 11:55 ` [PATCH v9 10/18] PCI/P2PDMA: Route Translated Requests under Direct Translated P2P Leon Romanovsky
2026-10-06 22:28 ` Bjorn Helgaas
2026-10-01 11:55 ` [PATCH v9 11/18] PCI/P2PDMA: Log detailed ACS routing diagnostics Leon Romanovsky
2026-10-01 11:55 ` [PATCH v9 12/18] PCI/P2PDMA: Add KUnit tests for the ACS routing decisions Leon Romanovsky
2026-10-01 11:55 ` [PATCH v9 13/18] PCI/P2PDMA: Test the ACS P2P routing walk Leon Romanovsky
2026-10-01 11:55 ` [PATCH v9 14/18] PCI: Add KUnit coverage for ACS isolation checks Leon Romanovsky
2026-10-01 11:55 ` [PATCH v9 15/18] PCI/P2PDMA: Document TLP-class routing Leon Romanovsky
2026-10-01 11:55 ` [PATCH v9 16/18] PCI/P2PDMA: Let a client declare that it selects ATS per mapping Leon Romanovsky
2026-10-01 11:55 ` [PATCH v9 17/18] PCI/P2PDMA: Evaluate the ATS path for clients with ATS enabled Leon Romanovsky
2026-10-01 11:55 ` [PATCH v9 18/18] PCI/P2PDMA: Test the routing of " Leon Romanovsky
2026-10-06 19:29 ` [PATCH v9 00/18] PCI/P2PDMA: Route peer-to-peer DMA by TLP class Bjorn Helgaas
2026-10-06 21:22 ` Leon Romanovsky
2026-10-06 21:36 ` Bjorn Helgaas
2026-10-07 6:56 ` Bjorn Helgaas
2026-10-07 10:54 ` Leon Romanovsky
2026-10-07 11:31 ` Bjorn Helgaas
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