From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Eric Anholt <eric@anholt.net>
Cc: Daniel Vetter <daniel@ffwll.ch>,
devicetree@vger.kernel.org,
Stephen Warren <swarren@wwwdotorg.org>,
Lee Jones <lee@kernel.org>,
linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
linux-rpi-kernel@lists.infradead.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 3/7] drm/vc4: Add KMS support for Raspberry Pi.
Date: Thu, 13 Aug 2015 22:29:36 +0100 [thread overview]
Message-ID: <20150813212936.GT7557@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <87d1yqq5po.fsf@eliezer.anholt.net>
On Thu, Aug 13, 2015 at 01:44:03PM -0700, Eric Anholt wrote:
> Struct mutex is here because this code is from the V3D series, with the
> in-kernel BO cache ripped out (it turns out that the CMA allocator is
> slow, and you can't just userspace cache since we have to do allocations
> within the kernel to the tune of a couple per draw and that's too much).
The CMA allocator is fast until you have pinned pages in its region,
where it becomes _very_ slow to do allocations, sometimes getting up
to the order of seconds.
The main culpret of this are GFP_HIGHUSER_MOVABLE allocations which
then pin the page. It doesn't take many of those to make CMA really
inefficient.
The problem is that CMA doesn't get any information back from the
internal page migration about which pages couldn't be moved, so it
dumbly just tries incrementing the allocation by one page (subject
to alignment constraints) and retrying again - repeating over the
entire CMA region. The bigger the region, the more time this takes.
--
FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up
according to speedtest.net.
WARNING: multiple messages have this Message-ID (diff)
From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Eric Anholt <eric@anholt.net>
Cc: devicetree@vger.kernel.org,
Stephen Warren <swarren@wwwdotorg.org>,
Lee Jones <lee@kernel.org>,
linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
linux-rpi-kernel@lists.infradead.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 3/7] drm/vc4: Add KMS support for Raspberry Pi.
Date: Thu, 13 Aug 2015 22:29:36 +0100 [thread overview]
Message-ID: <20150813212936.GT7557@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <87d1yqq5po.fsf@eliezer.anholt.net>
On Thu, Aug 13, 2015 at 01:44:03PM -0700, Eric Anholt wrote:
> Struct mutex is here because this code is from the V3D series, with the
> in-kernel BO cache ripped out (it turns out that the CMA allocator is
> slow, and you can't just userspace cache since we have to do allocations
> within the kernel to the tune of a couple per draw and that's too much).
The CMA allocator is fast until you have pinned pages in its region,
where it becomes _very_ slow to do allocations, sometimes getting up
to the order of seconds.
The main culpret of this are GFP_HIGHUSER_MOVABLE allocations which
then pin the page. It doesn't take many of those to make CMA really
inefficient.
The problem is that CMA doesn't get any information back from the
internal page migration about which pages couldn't be moved, so it
dumbly just tries incrementing the allocation by one page (subject
to alignment constraints) and retrying again - repeating over the
entire CMA region. The bigger the region, the more time this takes.
--
FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up
according to speedtest.net.
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/dri-devel
WARNING: multiple messages have this Message-ID (diff)
From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 3/7] drm/vc4: Add KMS support for Raspberry Pi.
Date: Thu, 13 Aug 2015 22:29:36 +0100 [thread overview]
Message-ID: <20150813212936.GT7557@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <87d1yqq5po.fsf@eliezer.anholt.net>
On Thu, Aug 13, 2015 at 01:44:03PM -0700, Eric Anholt wrote:
> Struct mutex is here because this code is from the V3D series, with the
> in-kernel BO cache ripped out (it turns out that the CMA allocator is
> slow, and you can't just userspace cache since we have to do allocations
> within the kernel to the tune of a couple per draw and that's too much).
The CMA allocator is fast until you have pinned pages in its region,
where it becomes _very_ slow to do allocations, sometimes getting up
to the order of seconds.
The main culpret of this are GFP_HIGHUSER_MOVABLE allocations which
then pin the page. It doesn't take many of those to make CMA really
inefficient.
The problem is that CMA doesn't get any information back from the
internal page migration about which pages couldn't be moved, so it
dumbly just tries incrementing the allocation by one page (subject
to alignment constraints) and retrying again - repeating over the
entire CMA region. The bigger the region, the more time this takes.
--
FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up
according to speedtest.net.
next prev parent reply other threads:[~2015-08-13 21:29 UTC|newest]
Thread overview: 101+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-13 0:56 Raspberry Pi KMS-only driver Eric Anholt
2015-08-13 0:56 ` Eric Anholt
2015-08-13 0:56 ` Eric Anholt
2015-08-13 0:56 ` [PATCH 1/7] drm/vc4: Add devicetree bindings for VC4 Eric Anholt
2015-08-13 0:56 ` Eric Anholt
2015-08-13 0:56 ` Eric Anholt
2015-08-15 4:38 ` Stephen Warren
2015-08-15 4:38 ` Stephen Warren
2015-08-17 18:30 ` Eric Anholt
2015-08-17 18:30 ` Eric Anholt
2015-08-17 18:30 ` Eric Anholt
2015-08-24 13:47 ` Rob Herring
2015-08-24 13:47 ` Rob Herring
2015-08-24 13:47 ` Rob Herring
2015-08-25 20:42 ` Rob Clark
2015-08-25 20:42 ` Rob Clark
2015-08-25 20:42 ` Rob Clark
2015-08-25 23:22 ` Rob Herring
2015-08-25 23:22 ` Rob Herring
2015-08-25 23:22 ` Rob Herring
2015-08-26 11:52 ` Daniel Vetter
2015-08-26 11:52 ` Daniel Vetter
2015-08-26 11:52 ` Daniel Vetter
2015-08-26 12:09 ` Thierry Reding
2015-08-26 12:09 ` Thierry Reding
2015-08-26 12:09 ` Thierry Reding
2015-08-26 14:30 ` Rob Herring
2015-08-26 14:30 ` Rob Herring
2015-08-26 14:30 ` Rob Herring
2015-08-26 20:59 ` Dave Airlie
2015-08-26 20:59 ` Dave Airlie
2015-08-26 20:59 ` Dave Airlie
2015-08-27 0:35 ` Rob Herring
2015-08-27 0:35 ` Rob Herring
2015-08-27 0:35 ` Rob Herring
2015-08-26 11:51 ` Thierry Reding
2015-08-26 11:51 ` Thierry Reding
2015-08-26 11:51 ` Thierry Reding
2015-08-24 13:56 ` Rob Herring
2015-08-24 13:56 ` Rob Herring
2015-08-24 13:56 ` Rob Herring
2015-08-13 0:56 ` [PATCH 2/7] MAINTAINERS: Add myself for the new VC4 (RPi GPU) graphics driver Eric Anholt
2015-08-13 0:56 ` Eric Anholt
2015-08-13 0:56 ` Eric Anholt
2015-08-15 4:39 ` Stephen Warren
2015-08-15 4:39 ` Stephen Warren
2015-08-15 4:39 ` Stephen Warren
2015-08-17 18:47 ` Eric Anholt
2015-08-17 18:47 ` Eric Anholt
2015-08-17 18:47 ` Eric Anholt
2015-08-13 0:56 ` [PATCH 3/7] drm/vc4: Add KMS support for Raspberry Pi Eric Anholt
2015-08-13 0:56 ` Eric Anholt
2015-08-13 0:56 ` Eric Anholt
2015-08-13 7:51 ` Daniel Vetter
2015-08-13 7:51 ` Daniel Vetter
2015-08-13 7:51 ` Daniel Vetter
2015-08-13 20:44 ` Eric Anholt
2015-08-13 20:44 ` Eric Anholt
2015-08-13 20:44 ` Eric Anholt
2015-08-13 21:17 ` Daniel Vetter
2015-08-13 21:17 ` Daniel Vetter
2015-08-13 21:17 ` Daniel Vetter
2015-08-18 20:56 ` Eric Anholt
2015-08-18 20:56 ` Eric Anholt
2015-08-18 20:56 ` Eric Anholt
2015-08-13 21:29 ` Russell King - ARM Linux [this message]
2015-08-13 21:29 ` Russell King - ARM Linux
2015-08-13 21:29 ` Russell King - ARM Linux
2015-08-13 23:03 ` Eric Anholt
2015-08-13 23:03 ` Eric Anholt
2015-08-13 23:03 ` Eric Anholt
2015-08-13 11:45 ` Emil Velikov
2015-08-13 11:45 ` Emil Velikov
2015-08-13 11:45 ` Emil Velikov
2015-08-15 4:45 ` Stephen Warren
2015-08-15 4:45 ` Stephen Warren
2015-08-15 4:45 ` Stephen Warren
2015-08-17 17:56 ` Eric Anholt
2015-08-17 17:56 ` Eric Anholt
2015-08-17 17:56 ` Eric Anholt
2015-08-13 0:56 ` [PATCH 4/7] drm/vc4: Use the fbdev_cma helpers Eric Anholt
2015-08-13 0:56 ` Eric Anholt
2015-08-13 0:56 ` Eric Anholt
2015-08-13 0:56 ` [PATCH 5/7] drm/vc4: Allow vblank to be disabled Eric Anholt
2015-08-13 0:56 ` Eric Anholt
2015-08-13 0:56 ` Eric Anholt
2015-08-13 0:56 ` [PATCH 6/7] ARM: bcm2835: Add the DDC I2C controller to the device tree Eric Anholt
2015-08-13 0:56 ` Eric Anholt
2015-08-13 0:56 ` Eric Anholt
2015-08-15 4:51 ` Stephen Warren
2015-08-15 4:51 ` Stephen Warren
2015-08-15 4:51 ` Stephen Warren
2015-08-17 18:35 ` Eric Anholt
2015-08-17 18:35 ` Eric Anholt
2015-08-17 18:35 ` Eric Anholt
2015-08-13 0:56 ` [PATCH 7/7] ARM: bcm2835: Add VC4 " Eric Anholt
2015-08-13 0:56 ` Eric Anholt
2015-08-13 0:56 ` Eric Anholt
2015-08-15 4:54 ` Stephen Warren
2015-08-15 4:54 ` Stephen Warren
2015-08-15 4:54 ` Stephen Warren
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