[Intel-gfx] [PATCH 2/6] drm/i915/gem: Almagamate clflushes on freeze

[Guenter Roeck]

On Tue, Jan 19, 2021 at 02:49:08PM +0000, Chris Wilson wrote:
> When flushing objects larger than the CPU cache it is preferrable to use
> a single wbinvd() rather than overlapping clflush(). At runtime, we
> avoid wbinvd() due to its system-wide latencies, but during
> singlethreaded suspend, no one will observe the imposed latency and we
> can opt for the faster wbinvd to clear all objects in a single hit.
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Reviewed-by: Matthew Auld <matthew.auld at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_gem.c | 16 +++++-----------
>  1 file changed, 5 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index c013148835e6..d3a287bf56c5 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -1175,19 +1175,13 @@ int i915_gem_freeze_late(struct drm_i915_private *i915)
>  	 * the objects as well, see i915_gem_freeze()
>  	 */
>  
> -	wakeref = intel_runtime_pm_get(&i915->runtime_pm);
> -
> -	i915_gem_shrink(i915, -1UL, NULL, ~0);
> +	with_intel_runtime_pm(&i915->runtime_pm, wakeref)
> +		i915_gem_shrink(i915, -1UL, NULL, ~0);
>  	i915_gem_drain_freed_objects(i915);
>  
> -	list_for_each_entry(obj, &i915->mm.shrink_list, mm.link) {
> -		i915_gem_object_lock(obj, NULL);
> -		drm_WARN_ON(&i915->drm,
> -			    i915_gem_object_set_to_cpu_domain(obj, true));
> -		i915_gem_object_unlock(obj);
> -	}
> -
> -	intel_runtime_pm_put(&i915->runtime_pm, wakeref);
> +	wbinvd_on_all_cpus();

with CONFIG_SMP=n, this results in:

drivers/gpu/drm/i915/i915_gem.c: In function 'i915_gem_freeze_late':
drivers/gpu/drm/i915/i915_gem.c:1182:2: error: implicit declaration of function 'wbinvd_on_all_cpus'

Other drivers calling this function include <asm/smp.h>.

Guenter

> +	list_for_each_entry(obj, &i915->mm.shrink_list, mm.link)
> +		__start_cpu_write(obj);
>  
>  	return 0;
>  }