From: Rob Herring <robh@kernel.org>
To: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>,
Neil Armstrong <narmstrong@baylibre.com>,
Robin Murphy <robin.murphy@arm.com>,
dri-devel <dri-devel@lists.freedesktop.org>,
Steven Price <steven.price@arm.com>,
Linux IOMMU <iommu@lists.linux-foundation.org>,
Kevin Hilman <khilman@baylibre.com>,
"open list:ARM/Amlogic Meson..."
<linux-amlogic@lists.infradead.org>,
Will Deacon <will@kernel.org>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
Jerome Brunet <jbrunet@baylibre.com>
Subject: Re: [PATCH 0/3] drm: panfrost: Coherency support
Date: Wed, 16 Sep 2020 11:46:31 -0600 [thread overview]
Message-ID: <CAL_JsqLGO4YYPjQsjnzZCW5iT6n+keZw9G9mFALJip0nDo42Hw@mail.gmail.com> (raw)
In-Reply-To: <20200916170409.GA2543@kevin>
On Wed, Sep 16, 2020 at 11:04 AM Alyssa Rosenzweig
<alyssa.rosenzweig@collabora.com> wrote:
>
> > So I get a performance regression with the dma-coherent approach, even if it's
> > clearly the cleaner.
>
> That's bizarre -- this should really be the faster of the two.
Coherency may not be free. CortexA9 had something like 4x slower
memcpy if SMP was enabled as an example. I don't know if there's
anything going on like that specifically here. If there's never any
CPU accesses mixed in with kmscube, then there would be no benefit to
coherency.
Rob
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next prev parent reply other threads:[~2020-09-16 17:47 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-15 23:51 [PATCH 0/3] drm: panfrost: Coherency support Robin Murphy
2020-09-15 23:51 ` [PATCH 1/3] iommu/io-pgtable-arm: Support coherency for Mali LPAE Robin Murphy
2020-09-21 17:57 ` Will Deacon
2020-09-21 21:53 ` Robin Murphy
2020-09-21 22:24 ` Will Deacon
2020-09-15 23:51 ` [PATCH 2/3] drm/panfrost: Support cache-coherent integrations Robin Murphy
2020-09-17 10:37 ` Steven Price
2020-09-15 23:51 ` [PATCH 3/3] arm64: dts: meson: Describe G12b GPU as coherent Robin Murphy
2020-09-16 8:26 ` Neil Armstrong
2020-10-05 8:15 ` Boris Brezillon
2020-10-05 8:34 ` Steven Price
2020-10-05 8:39 ` Boris Brezillon
2020-10-05 10:05 ` Steven Price
2020-09-16 14:54 ` Neil Armstrong
2020-09-16 14:54 ` [PATCH 0/3] drm: panfrost: Coherency support Neil Armstrong
2020-09-16 17:04 ` Alyssa Rosenzweig
2020-09-16 17:46 ` Rob Herring [this message]
2020-09-17 10:38 ` Steven Price
2020-09-17 10:51 ` Tomeu Vizoso
2020-09-17 11:00 ` Steven Price
2020-09-17 12:03 ` Alyssa Rosenzweig
2020-09-17 12:38 ` Robin Murphy
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