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From: Chris Wilson <chris@chris-wilson.co.uk>
To: Ben Widawsky <ben@bwidawsk.net>
Cc: dri-devel@lists.freedestkop.org, Dave Airlie <airlied@redhat.com>,
	intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH 01/18] drm: Introduce drm_mm_create_block()
Date: Sun, 28 Oct 2012 09:57:21 +0000	[thread overview]
Message-ID: <b94cdc$74b5g6@fmsmga001.fm.intel.com> (raw)
In-Reply-To: <20121026144743.6d168d86@bwidawsk.net>

On Fri, 26 Oct 2012 14:47:43 -0700, Ben Widawsky <ben@bwidawsk.net> wrote:
> On Fri, 19 Oct 2012 18:03:07 +0100
> Chris Wilson <chris@chris-wilson.co.uk> wrote:
> 
> > To be used later by i915 to preallocate exact blocks of space from the
> > range manager.
> > 
> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Cc: Dave Airlie <airlied@redhat.com>
> > Cc: dri-devel@lists.freedestkop.org
> 
> With bikesheds below addressed or not:
> Reviewed-by: Ben Widawsky <ben@bwidawsk.net>
> > ---
> >  drivers/gpu/drm/drm_mm.c |   49
> > ++++++++++++++++++++++++++++++++++++++++++++++
> > include/drm/drm_mm.h     |    4 ++++ 2 files changed, 53 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c
> > index 9bb82f7..5db8c20 100644
> > --- a/drivers/gpu/drm/drm_mm.c
> > +++ b/drivers/gpu/drm/drm_mm.c
> > @@ -161,6 +161,55 @@ static void drm_mm_insert_helper(struct
> > drm_mm_node *hole_node, }
> >  }
> >  
> > +struct drm_mm_node *drm_mm_create_block(struct drm_mm *mm,
> > +					unsigned long start,
> > +					unsigned long size,
> > +					bool atomic)
> > +{
> 
> <bikeshed>
> You could add a best_fit field like some of the other interfaces which
> will try to find a start == hole_start and end == hole_end. I'd guess
> this interface won't be called enough to worry about fragmentation too
> much though.
> </bikeshed>

It's not a best fit though, it's an exact allocation request. The search
is to find the location in the free list where we need to insert the
node, and just as importantly reject the request if it would clobber an
earlier allocation.

> 
> > +	struct drm_mm_node *hole, *node;
> > +	unsigned long end = start + size;
> > +
> > +	list_for_each_entry(hole, &mm->hole_stack, hole_stack) {
> > +		unsigned long hole_start;
> > +		unsigned long hole_end;
> > +
> > +		BUG_ON(!hole->hole_follows);
> 
> <bikeshed>
> This isn't bad, but I don't think sticking the bug here is all that
> helpful in finding where the bug occured, since it wasn't here. WARN is
> perhaps more useful, but equally unhelpful IMO.
> </bikeshed>

The BUG_ON() is to be consistent with the rest of the code, and so there
isn't a conflict of interests when replacing all the common chunks with
drm_mm_for_each_hole().
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre

  reply	other threads:[~2012-10-28 10:08 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-10-19 17:03 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
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 [this message]
2012-10-28 18:12     ` Ben Widawsky
2012-10-28 18:14       ` Ben Widawsky

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