[Intel-gfx] [PATCH] drm/agp: agp-intel/i915: trim stolen space to 16M

[Zhenyu Wang]

On 2010.03.22 11:17:46 -0700, Jesse Barnes wrote:
> On my SDV, the BIOS allocates 128M of stolen space no matter what
> settings I use.  This leaves very little aperture space available (at
> least relatively so given my 30" + 24" desktop setup) for mapping
> buffers in execbuf.
> 
> I've been using this patch for awhile to work around the problem, and
> think it's a reasonable thing to apply.  We generally only need a small
> amount of stolen space for the few things that need contiguous space,
> the compressed frame buffer being the biggest.

Jesse, from Yakui's recent finding, the compressed fb size for Cantiga
and Ironlake could be as large as 4096x2048 32bpc for 32MB, so some large
fb size e.g 1900x1200 could be compressed. So max 16M for stolen may be
too small?

I'll send out Yakui's patch later.

> 
> I think I have an idea of how to reclaim the space and give it back to
> linux, but I haven't tested that yet; I'll post a follow-up patch on
> top of this one when I have it working (basically changing the memory
> back to WB using MTRR and/or set_memory_* calls and using memory
> hotplug's add_memory() call to return it to the system).
> 
> Signed-off-by: Jesse Barnes <jbarnes at virtuousgeek.org>
> 
> diff --git a/drivers/char/agp/intel-agp.c b/drivers/char/agp/intel-agp.c
> index c1c07a2..5a2be66 100644
> --- a/drivers/char/agp/intel-agp.c
> +++ b/drivers/char/agp/intel-agp.c
> @@ -13,6 +13,10 @@
>  int intel_agp_enabled;
>  EXPORT_SYMBOL(intel_agp_enabled);
>  
> +/* Max amount of stolen space, anything above will be returned to Linux */
> +int intel_max_stolen = 16 * 1024 * 1024;
> +EXPORT_SYMBOL(intel_max_stolen);
> +
>  /*
>   * If we have Intel graphics, we're not going to have anything other than
>   * an Intel IOMMU. So make the correct use of the PCI DMA API contingent
> @@ -869,7 +873,13 @@ static void intel_i830_init_gtt_entries(void)
>  			break;
>  		}
>  	}
> -	if (gtt_entries > 0) {
> +
> +	if (!local && gtt_entries > intel_max_stolen) {
> +		dev_info(&agp_bridge->dev->dev,
> +			 "detected %dK stolen memory, trimming to %dK\n",
> +			 gtt_entries / KB(1), intel_max_stolen / KB(1));
> +		gtt_entries = intel_max_stolen / KB(4);
> +	} else if (gtt_entries > 0) {
>  		dev_info(&agp_bridge->dev->dev, "detected %dK %s memory\n",
>  		       gtt_entries / KB(1), local ? "local" : "stolen");
>  		gtt_entries /= KB(4);
> diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
> index b63638a..6a428b2 100644
> --- a/drivers/gpu/drm/i915/i915_dma.c
> +++ b/drivers/gpu/drm/i915/i915_dma.c
> @@ -38,6 +38,8 @@
>  #include <linux/acpi.h>
>  #include <linux/pnp.h>
>  
> +extern int intel_max_stolen; /* from AGP driver */
> +
>  /* Really want an OS-independent resettable timer.  Would like to have
>   * this loop run for (eg) 3 sec, but have the timer reset every time
>   * the head pointer changes, so that EBUSY only happens if the ring
> @@ -1608,6 +1610,12 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
>  	if (ret)
>  		goto out_iomapfree;
>  
> +	if (prealloc_size > intel_max_stolen) {
> +		DRM_INFO("detected %dM stolen memory, trimming to %dM\n",
> +			 prealloc_size >> 20, intel_max_stolen >> 20);
> +		prealloc_size = intel_max_stolen;
> +	}
> +
>  	dev_priv->wq = create_singlethread_workqueue("i915");
>  	if (dev_priv->wq == NULL) {
>  		DRM_ERROR("Failed to create our workqueue.\n");
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Open Source Technology Center, Intel ltd.

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