Re: [PATCH] drm/i915/gem: Make i915_gem_shrinker multi-gt aware

[Andrzej Hajda <andrzej.hajda@xxxxxxxxx>]

On 22.09.2023 14:35, Nirmoy Das wrote:
> From: Jonathan Cavitt <jonathan.cavitt@xxxxxxxxx>
>
> Where applicable, use for_each_gt instead of to_gt in the
> i915_gem_shrinker functions to make them apply to more than just the
> primary GT.  Specifically, this ensure i915_gem_shrink_all retires all
> requests across all GTs, and this makes i915_gem_shrinker_vmap unmap
> VMAs from all GTs.
>
> Signed-off-by: Jonathan Cavitt <jonathan.cavitt@xxxxxxxxx>
> Signed-off-by: Nirmoy Das <nirmoy.das@xxxxxxxxx>
> ---
>   drivers/gpu/drm/i915/gem/i915_gem_shrinker.c | 44 ++++++++++++--------
>   1 file changed, 26 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shrinker.c b/drivers/gpu/drm/i915/gem/i915_gem_shrinker.c
> index 214763942aa2..3ef1fd32f80a 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_shrinker.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_shrinker.c
> @@ -14,6 +14,7 @@
>   #include <linux/vmalloc.h>
>   
>   #include "gt/intel_gt_requests.h"
> +#include "gt/intel_gt.h"
>   
>   #include "i915_trace.h"
>   
> @@ -119,7 +120,8 @@ i915_gem_shrink(struct i915_gem_ww_ctx *ww,
>   	intel_wakeref_t wakeref = 0;
>   	unsigned long count = 0;
>   	unsigned long scanned = 0;
> -	int err = 0;
> +	int err = 0, i = 0;
> +	struct intel_gt *gt;
>   
>   	/* CHV + VTD workaround use stop_machine(); need to trylock vm->mutex */
>   	bool trylock_vm = !ww && intel_vm_no_concurrent_access_wa(i915);
> @@ -147,9 +149,11 @@ i915_gem_shrink(struct i915_gem_ww_ctx *ww,
>   	 * what we can do is give them a kick so that we do not keep idle
>   	 * contexts around longer than is necessary.
>   	 */
> -	if (shrink & I915_SHRINK_ACTIVE)
> -		/* Retire requests to unpin all idle contexts */
> -		intel_gt_retire_requests(to_gt(i915));
> +	if (shrink & I915_SHRINK_ACTIVE) {
> +		for_each_gt(gt, i915, i)
> +			/* Retire requests to unpin all idle contexts */
> +			intel_gt_retire_requests(to_gt(i915));


to_gt(...) -> gt ?


> +	}
>   
>   	/*
>   	 * As we may completely rewrite the (un)bound list whilst unbinding
> @@ -389,6 +393,8 @@ i915_gem_shrinker_vmap(struct notifier_block *nb, unsigned long event, void *ptr
>   	struct i915_vma *vma, *next;
>   	unsigned long freed_pages = 0;
>   	intel_wakeref_t wakeref;
> +	struct intel_gt *gt;
> +	int i;
>   
>   	with_intel_runtime_pm(&i915->runtime_pm, wakeref)
>   		freed_pages += i915_gem_shrink(NULL, i915, -1UL, NULL,
> @@ -397,24 +403,26 @@ i915_gem_shrinker_vmap(struct notifier_block *nb, unsigned long event, void *ptr
>   					       I915_SHRINK_VMAPS);
>   
>   	/* We also want to clear any cached iomaps as they wrap vmap */
> -	mutex_lock(&to_gt(i915)->ggtt->vm.mutex);
> -	list_for_each_entry_safe(vma, next,
> -				 &to_gt(i915)->ggtt->vm.bound_list, vm_link) {
> -		unsigned long count = i915_vma_size(vma) >> PAGE_SHIFT;
> -		struct drm_i915_gem_object *obj = vma->obj;
> -
> -		if (!vma->iomap || i915_vma_is_active(vma))
> -			continue;
> +	for_each_gt(gt, i915, i) {
> +		mutex_lock(&gt->ggtt->vm.mutex);
> +		list_for_each_entry_safe(vma, next,
> +					 &gt->ggtt->vm.bound_list, vm_link) {
> +			unsigned long count = i915_vma_size(vma) >> PAGE_SHIFT;
> +			struct drm_i915_gem_object *obj = vma->obj;
> +
> +			if (!vma->iomap || i915_vma_is_active(vma))
> +				continue;
>   
> -		if (!i915_gem_object_trylock(obj, NULL))
> -			continue;
> +			if (!i915_gem_object_trylock(obj, NULL))
> +				continue;
>   
> -		if (__i915_vma_unbind(vma) == 0)
> -			freed_pages += count;
> +			if (__i915_vma_unbind(vma) == 0)
> +				freed_pages += count;
>   
> -		i915_gem_object_unlock(obj);
> +			i915_gem_object_unlock(obj);
> +		}
> +		mutex_unlock(&gt->ggtt->vm.mutex);
>   	}
> -	mutex_unlock(&to_gt(i915)->ggtt->vm.mutex);


This seems correct.

With 1st stanza fixed:
Reviewed-by: Andrzej Hajda <andrzej.hajda@xxxxxxxxx>

Regards
Andrzej


>   
>   	*(unsigned long *)ptr += freed_pages;
>   	return NOTIFY_DONE;