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From: Jesse Barnes <jbarnes@virtuousgeek.org>
To: Chris Wilson <chris@chris-wilson.co.uk>
Cc: intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH 18/18] drm/i915: Introduce mapping of user pages into video memory (userptr) ioctl
Date: Mon, 22 Oct 2012 15:21:10 -0700	[thread overview]
Message-ID: <20121022152110.6c983c10@jbarnes-desktop> (raw)
In-Reply-To: <1350666204-8101-18-git-send-email-chris@chris-wilson.co.uk>

On Fri, 19 Oct 2012 18:03:24 +0100
Chris Wilson <chris@chris-wilson.co.uk> wrote:

> By exporting the ability to map user address and inserting PTEs
> representing their backing pages into the GTT, we can exploit UMA in order
> to utilize normal application data as a texture source or even as a
> render target (depending upon the capabilities of the chipset). This has
> a number of uses, with zero-copy downloads to the GPU and efficient
> readback making the intermixed streaming of CPU and GPU operations
> fairly efficient. This ability has many widespread implications from
> faster rendering of client-side software rasterisers (chromium),
> mitigation of stalls due to read back (firefox) and to faster pipelining
> of texture data (such as pixel buffer objects in GL).
> 
> v2: Compile with CONFIG_MMU_NOTIFIER

I want to understand the root-only nature of this better.

Is locking complexity the only reason we can't treat these pages like
normal BOs which can be swapped out from under us as long as they're
not pinned into the GTT?  Or are there other complications in managing
the refcount for these pages?

Reminds me: do we also check our bo allocations against the current
task's address space, data, file size, locked memory, file count,
and rss limits?  I dug into the shmem code at one point and seem to
remember that we didn't.  If not, it might be a good thing to add under
a new config option at some point.

-- 
Jesse Barnes, Intel Open Source Technology Center

  reply	other threads:[~2012-10-22 22:20 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-10-19 17:03 [PATCH 01/18] drm: Introduce drm_mm_create_block() Chris Wilson
2012-10-19 17:03 ` [PATCH 02/18] drm/i915: Fix detection of stolen base for gen2 Chris Wilson
2012-11-01 23:51   ` Ben Widawsky
2012-10-19 17:03 ` [PATCH 03/18] drm/i915: Fix location of stolen memory register for SandyBridge+ Chris Wilson
2012-10-26 21:58   ` Ben Widawsky
2012-10-28  9:48     ` Chris Wilson
2012-10-28 17:52       ` Ben Widawsky
2012-11-02  0:08       ` Ben Widawsky
2012-11-02  8:54         ` Chris Wilson
2012-11-05 13:53           ` Ben Widawsky
2012-10-19 17:03 ` [PATCH 04/18] drm/i915: Avoid clearing preallocated regions from the GTT Chris Wilson
2012-10-26 22:22   ` Ben Widawsky
2012-10-19 17:03 ` [PATCH 05/18] drm: Introduce an iterator over holes in the drm_mm range manager Chris Wilson
2012-11-05 13:41   ` Ben Widawsky
2012-11-05 15:13     ` Chris Wilson
2012-10-19 17:03 ` [PATCH 06/18] drm/i915: Delay allocation of stolen space for FBC Chris Wilson
2012-11-05 13:44   ` Ben Widawsky
2012-11-05 15:24     ` Chris Wilson
2012-10-19 17:03 ` [PATCH 07/18] drm/i915: Defer allocation of stolen memory for FBC until actual first use Chris Wilson
2012-11-05 15:00   ` Ben Widawsky
2012-11-05 15:28     ` Chris Wilson
2012-11-05 15:32       ` Ben Widawsky
2012-10-19 17:03 ` [PATCH 08/18] drm/i915: Allow objects to be created with no backing pages, but stolen space Chris Wilson
2012-10-19 17:03 ` [PATCH 09/18] drm/i915: Differentiate between prime and stolen objects Chris Wilson
2012-10-19 17:03 ` [PATCH 10/18] drm/i915: Support readback of stolen objects upon error Chris Wilson
2012-11-05 15:41   ` Ben Widawsky
2012-10-19 17:03 ` [PATCH 11/18] drm/i915: Handle stolen objects in pwrite Chris Wilson
2012-10-19 17:03 ` [PATCH 12/18] drm/i915: Handle stolen objects for pread Chris Wilson
2012-10-19 17:03 ` [PATCH 13/18] drm/i915: Introduce i915_gem_object_create_stolen() Chris Wilson
2012-11-05 16:32   ` Ben Widawsky
2012-11-05 16:59     ` Chris Wilson
2012-11-05 17:34       ` Ben Widawsky
2012-10-19 17:03 ` [PATCH 14/18] drm/i915: Allocate fbcon from stolen memory Chris Wilson
2012-10-19 17:03 ` [PATCH 15/18] drm/i915: Allocate ringbuffers " Chris Wilson
2012-10-19 17:03 ` [PATCH 16/18] drm/i915: Allocate overlay registers " Chris Wilson
2012-11-05 17:39   ` Ben Widawsky
2012-10-19 17:03 ` [PATCH 17/18] drm/i915: Use a slab for object allocation Chris Wilson
2012-10-24 20:21   ` Paulo Zanoni
2012-11-05 17:49   ` Ben Widawsky
2012-11-05 20:57     ` Chris Wilson
2012-11-07 13:59       ` Ben Widawsky
2012-11-05 18:07   ` Ben Widawsky
2012-11-05 18:10     ` Ben Widawsky
2012-10-19 17:03 ` [PATCH 18/18] drm/i915: Introduce mapping of user pages into video memory (userptr) ioctl Chris Wilson
2012-10-22 22:21   ` Jesse Barnes [this message]
2012-10-23  7:20     ` Daniel Vetter
2012-10-23 17:50       ` Eric Anholt
2012-10-26 21:47 ` [PATCH 01/18] drm: Introduce drm_mm_create_block() Ben Widawsky
2012-10-28  9:57   ` Chris Wilson
2012-10-28 18:12     ` Ben Widawsky
2012-10-28 18:14       ` Ben Widawsky

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