From: Jason Gunthorpe <jgg@nvidia.com>
To: Will Deacon <will@kernel.org>
Cc: Mostafa Saleh <smostafa@google.com>,
Daniel Mentz <danielmentz@google.com>,
iommu@lists.linux.dev, linux-kernel@vger.kernel.org,
Pranjal Shrivastava <praan@google.com>,
Liviu Dudau <liviu.dudau@arm.com>,
Rob Clark <robin.clark@oss.qualcomm.com>
Subject: Re: [PATCH 1/2] iommu/io-pgtable-arm: Implement .iotlb_sync_map callback
Date: Tue, 4 Nov 2025 09:37:24 -0400 [thread overview]
Message-ID: <20251104133724.GC1537560@nvidia.com> (raw)
In-Reply-To: <aQn_g85KI_uuYpJh@willie-the-truck>
On Tue, Nov 04, 2025 at 01:28:35PM +0000, Will Deacon wrote:
> If that's not workable (due to Daniel's performance worries), another
> option is to bring back the ->map_sg() hook (removed by d88e61faad52
> ("iommu: Remove the ->map_sg indirection")) and implement an optimised
> version of that, preferably sharing as much code as possible with the
> existing map path.
I've been broadly thinking of doing this. The benchmarks I've run
suggest there are decent gains in avoiding the re-walks, so we can
speed up the map_sg operation by working directly on the scatterlist
without rewalking every next sgent. That cleanly solves the CMO issue
as well.
I think the page table rework will land this cycle, that would be the
right time to attempt it as we should not be trying to make the
duplicated page table code any more complicated.
Jason
next prev parent reply other threads:[~2025-11-04 13:37 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-27 22:39 [PATCH 1/2] iommu/io-pgtable-arm: Implement .iotlb_sync_map callback Daniel Mentz
2025-09-27 22:39 ` [PATCH 2/2] drivers/arm-smmu-v3: " Daniel Mentz
2025-09-29 11:58 ` Jason Gunthorpe
2025-09-29 12:24 ` Mostafa Saleh
2025-09-29 12:47 ` Jason Gunthorpe
2025-09-30 0:23 ` Pranjal Shrivastava
2025-09-30 9:27 ` Mostafa Saleh
2025-09-30 14:56 ` Pranjal Shrivastava
2025-09-29 12:25 ` Mostafa Saleh
2025-09-29 12:21 ` [PATCH 1/2] iommu/io-pgtable-arm: " Mostafa Saleh
2025-09-29 21:00 ` Daniel Mentz
2025-09-30 9:10 ` Mostafa Saleh
2025-11-04 13:28 ` Will Deacon
2025-11-04 13:37 ` Jason Gunthorpe [this message]
2025-09-29 19:57 ` Pranjal Shrivastava
2025-09-29 20:42 ` Daniel Mentz
2025-09-29 22:24 ` Pranjal Shrivastava
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