From: Balbir Singh <balbirs@nvidia.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: iommu@lists.linux.dev, linux-kernel@vger.kernel.org,
"Marek Szyprowski" <m.szyprowski@samsung.com>,
"Robin Murphy" <robin.murphy@arm.com>,
"Christian König" <christian.koenig@amd.com>,
"Ingo Molnar" <mingo@kernel.org>, "Kees Cook" <kees@kernel.org>,
"Bjorn Helgaas" <bhelgaas@google.com>,
"Linus Torvalds" <torvalds@linux-foundation.org>,
"Peter Zijlstra" <peterz@infradead.org>,
"Andy Lutomirski" <luto@kernel.org>,
"Alex Deucher" <alexander.deucher@amd.com>,
"Bert Karwatzki" <spasswolf@web.de>
Subject: Re: [PATCH] dma/mapping.c: dev_dbg support for dma_addressing_limited
Date: Mon, 14 Apr 2025 21:36:51 +1000 [thread overview]
Message-ID: <f909b34f-784c-4439-928a-fe00ac34fb35@nvidia.com> (raw)
In-Reply-To: <Z_zuL6tIjeTLTNKK@infradead.org>
On 4/14/25 21:14, Christoph Hellwig wrote:
> On Mon, Apr 14, 2025 at 09:06:46PM +1000, Balbir Singh wrote:
>> + dev_dbg(dev, "might have lower perf due to bounce buffering\n");
>
> I don't think that's a good message. Report the actual observation,
> i.e. "device is DMA addressing limited" and not a guessed conclusion.
>
The bounce buffering remark came from the rest of the mention in code
and I agree the perf is based on my experience and may not be true
in all cases.
I'll respin
Balbir
prev parent reply other threads:[~2025-04-14 11:36 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-04-14 11:06 Balbir Singh
2025-04-14 11:14 ` Christoph Hellwig
2025-04-14 11:36 ` Balbir Singh [this message]
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