[Intel-gfx] [PATCH 1/3] drm/i915: add prefault_disable module option

[Daniel Vetter]

On Fri, Jul 19, 2013 at 01:51:24PM +0800, Xiong Zhang wrote:
> prefault is stll enabled by default which prevent most of pwrite/pread/reloc
> from running slow path, in order to verify these slow pathes, prefault need
> to be disabled.
> 
> Signed-off-by: Xiong Zhang <xiong.y.zhang at intel.com>

lgtm, queued for -next, thanks for the patch.
-Daniel

> ---
>  drivers/gpu/drm/i915/i915_drv.c            |  5 +++++
>  drivers/gpu/drm/i915/i915_drv.h            |  1 +
>  drivers/gpu/drm/i915/i915_gem.c            | 12 +++++++-----
>  drivers/gpu/drm/i915/i915_gem_execbuffer.c |  6 ++++--
>  4 files changed, 17 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index b07362f..dac6bd3 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -137,6 +137,11 @@ module_param_named(fastboot, i915_fastboot, bool, 0600);
>  MODULE_PARM_DESC(fastboot, "Try to skip unnecessary mode sets at boot time "
>  		 "(default: false)");
>  
> +bool i915_prefault_disable __read_mostly = false;
> +module_param_named(prefault_disable, i915_prefault_disable, bool, 0600);
> +MODULE_PARM_DESC(prefault_disable,
> +		"Try to disable pre page fault for pread/pwrite/reloc (default:false)");
> +
>  static struct drm_driver driver;
>  extern int intel_agp_enabled;
>  
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 7fdc8e3..9516e19 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1587,6 +1587,7 @@ extern unsigned int i915_preliminary_hw_support __read_mostly;
>  extern int i915_disable_power_well __read_mostly;
>  extern int i915_enable_ips __read_mostly;
>  extern bool i915_fastboot __read_mostly;
> +extern bool i915_prefault_disable __read_mostly;
>  
>  extern int i915_suspend(struct drm_device *dev, pm_message_t state);
>  extern int i915_resume(struct drm_device *dev);
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index c9d9d20..de59154 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -465,7 +465,7 @@ i915_gem_shmem_pread(struct drm_device *dev,
>  
>  		mutex_unlock(&dev->struct_mutex);
>  
> -		if (!prefaulted) {
> +		if (likely(!i915_prefault_disable) && !prefaulted) {
>  			ret = fault_in_multipages_writeable(user_data, remain);
>  			/* Userspace is tricking us, but we've already clobbered
>  			 * its pages with the prefault and promised to write the
> @@ -860,10 +860,12 @@ i915_gem_pwrite_ioctl(struct drm_device *dev, void *data,
>  		       args->size))
>  		return -EFAULT;
>  
> -	ret = fault_in_multipages_readable(to_user_ptr(args->data_ptr),
> -					   args->size);
> -	if (ret)
> -		return -EFAULT;
> +	if (likely(!i915_prefault_disable)) {
> +		ret = fault_in_multipages_readable(to_user_ptr(args->data_ptr),
> +						   args->size);
> +		if (ret)
> +			return -EFAULT;
> +	}
>  
>  	ret = i915_mutex_lock_interruptible(dev);
>  	if (ret)
> diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> index 1b58694..1734825 100644
> --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> @@ -759,8 +759,10 @@ validate_exec_list(struct drm_i915_gem_exec_object2 *exec,
>  		if (!access_ok(VERIFY_WRITE, ptr, length))
>  			return -EFAULT;
>  
> -		if (fault_in_multipages_readable(ptr, length))
> -			return -EFAULT;
> +		if (likely(!i915_prefault_disable)) {
> +			if (fault_in_multipages_readable(ptr, length))
> +				return -EFAULT;
> +		}
>  	}
>  
>  	return 0;
> -- 
> 1.8.3.2
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch