Re: [Intel-gfx] [PATCH v2 03/12] drm/i915/uapi: expose the avail tracking

["Thomas Hellström" <thomas.hellstrom@linux.intel.com>]

On Tue, 2022-06-21 at 11:44 +0100, Matthew Auld wrote:
> Vulkan would like to have a rough measure of how much device memory
> can
> in theory be allocated. Also add unallocated_cpu_visible_size to
> track
> the visible portion, in case the device is using small BAR. Also
> tweak
> the locking so we nice consistent values for both the mm->avail and
> the
> visible tracking.
> 
> v2: tweak the locking slightly so we update the mm->avail and visible
> tracking as one atomic operation, such that userspace doesn't get
> strange values when sampling the values.
> 
> Testcase: igt@i915_query@query-regions-unallocated
> Testcase: igt@i915_query@query-regions-sanity-check
> Signed-off-by: Matthew Auld <matthew.auld@intel.com>

Note the kernel test robot warning for inconsistent kerneldoc and
function name.

With that fixed,
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>


> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> Cc: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
> Cc: Jon Bloomfield <jon.bloomfield@intel.com>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: Jordan Justen <jordan.l.justen@intel.com>
> Cc: Kenneth Graunke <kenneth@whitecape.org>
> Cc: Akeem G Abodunrin <akeem.g.abodunrin@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_query.c             | 10 +++++-
>  drivers/gpu/drm/i915/i915_ttm_buddy_manager.c | 31 ++++++++++++++---
> --
>  drivers/gpu/drm/i915/i915_ttm_buddy_manager.h |  3 ++
>  drivers/gpu/drm/i915/intel_memory_region.c    | 14 +++++++++
>  drivers/gpu/drm/i915/intel_memory_region.h    |  3 ++
>  include/uapi/drm/i915_drm.h                   | 31
> ++++++++++++++++++-
>  6 files changed, 82 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_query.c
> b/drivers/gpu/drm/i915/i915_query.c
> index 9894add651dd..6ec9c9fb7b0d 100644
> --- a/drivers/gpu/drm/i915/i915_query.c
> +++ b/drivers/gpu/drm/i915/i915_query.c
> @@ -504,7 +504,15 @@ static int query_memregion_info(struct
> drm_i915_private *i915,
>                 else
>                         info.probed_cpu_visible_size = mr->total;
>  
> -               info.unallocated_size = mr->avail;
> +               if (perfmon_capable()) {
> +                       intel_memory_region_avail(mr,
> +                                                
> &info.unallocated_size,
> +                                                
> &info.unallocated_cpu_visible_size);
> +               } else {
> +                       info.unallocated_size = info.probed_size;
> +                       info.unallocated_cpu_visible_size =
> +                               info.probed_cpu_visible_size;
> +               }
>  
>                 if (__copy_to_user(info_ptr, &info, sizeof(info)))
>                         return -EFAULT;
> diff --git a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
> b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
> index a5109548abc0..864c8f55cacb 100644
> --- a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
> +++ b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
> @@ -104,18 +104,15 @@ static int i915_ttm_buddy_man_alloc(struct
> ttm_resource_manager *man,
>                                      min_page_size,
>                                      &bman_res->blocks,
>                                      bman_res->flags);
> -       mutex_unlock(&bman->lock);
>         if (unlikely(err))
>                 goto err_free_blocks;
>  
>         if (place->flags & TTM_PL_FLAG_CONTIGUOUS) {
>                 u64 original_size = (u64)bman_res->base.num_pages <<
> PAGE_SHIFT;
>  
> -               mutex_lock(&bman->lock);
>                 drm_buddy_block_trim(mm,
>                                      original_size,
>                                      &bman_res->blocks);
> -               mutex_unlock(&bman->lock);
>         }
>  
>         if (lpfn <= bman->visible_size) {
> @@ -137,11 +134,10 @@ static int i915_ttm_buddy_man_alloc(struct
> ttm_resource_manager *man,
>                 }
>         }
>  
> -       if (bman_res->used_visible_size) {
> -               mutex_lock(&bman->lock);
> +       if (bman_res->used_visible_size)
>                 bman->visible_avail -= bman_res->used_visible_size;
> -               mutex_unlock(&bman->lock);
> -       }
> +
> +       mutex_unlock(&bman->lock);
>  
>         if (place->lpfn - place->fpfn == n_pages)
>                 bman_res->base.start = place->fpfn;
> @@ -154,7 +150,6 @@ static int i915_ttm_buddy_man_alloc(struct
> ttm_resource_manager *man,
>         return 0;
>  
>  err_free_blocks:
> -       mutex_lock(&bman->lock);
>         drm_buddy_free_list(mm, &bman_res->blocks);
>         mutex_unlock(&bman->lock);
>  err_free_res:
> @@ -365,6 +360,26 @@ u64 i915_ttm_buddy_man_visible_size(struct
> ttm_resource_manager *man)
>         return bman->visible_size;
>  }
>  
> +/**
> + * i915_ttm_buddy_man_visible_size - Query the avail tracking for
> the manager.
> + *
> + * @man: The buddy allocator ttm manager
> + * @avail: The total available memory in pages for the entire
> manager.
> + * @visible_avail: The total available memory in pages for the CPU
> visible
> + * portion. Note that this will always give the same value as @avail
> on
> + * configurations that don't have a small BAR.
> + */
> +void i915_ttm_buddy_man_avail(struct ttm_resource_manager *man,
> +                            u64 *avail, u64 *visible_avail)
> +{
> +       struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);
> +
> +       mutex_lock(&bman->lock);
> +       *avail = bman->mm.avail >> PAGE_SHIFT;
> +       *visible_avail = bman->visible_avail;
> +       mutex_unlock(&bman->lock);
> +}
> +
>  #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
>  void i915_ttm_buddy_man_force_visible_size(struct
> ttm_resource_manager *man,
>                                            u64 size)
> diff --git a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.h
> b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.h
> index 52d9586d242c..d64620712830 100644
> --- a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.h
> +++ b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.h
> @@ -61,6 +61,9 @@ int i915_ttm_buddy_man_reserve(struct
> ttm_resource_manager *man,
>  
>  u64 i915_ttm_buddy_man_visible_size(struct ttm_resource_manager
> *man);
>  
> +void i915_ttm_buddy_man_avail(struct ttm_resource_manager *man,
> +                             u64 *avail, u64 *avail_visible);
> +
>  #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
>  void i915_ttm_buddy_man_force_visible_size(struct
> ttm_resource_manager *man,
>                                            u64 size);
> diff --git a/drivers/gpu/drm/i915/intel_memory_region.c
> b/drivers/gpu/drm/i915/intel_memory_region.c
> index e38d2db1c3e3..94ee26e99549 100644
> --- a/drivers/gpu/drm/i915/intel_memory_region.c
> +++ b/drivers/gpu/drm/i915/intel_memory_region.c
> @@ -279,6 +279,20 @@ void intel_memory_region_set_name(struct
> intel_memory_region *mem,
>         va_end(ap);
>  }
>  
> +void intel_memory_region_avail(struct intel_memory_region *mr,
> +                              u64 *avail, u64 *visible_avail)
> +{
> +       if (mr->type == INTEL_MEMORY_LOCAL) {
> +               i915_ttm_buddy_man_avail(mr->region_private,
> +                                        avail, visible_avail);
> +               *avail <<= PAGE_SHIFT;
> +               *visible_avail <<= PAGE_SHIFT;
> +       } else {
> +               *avail = mr->total;
> +               *visible_avail = mr->total;
> +       }
> +}
> +
>  void intel_memory_region_destroy(struct intel_memory_region *mem)
>  {
>         int ret = 0;
> diff --git a/drivers/gpu/drm/i915/intel_memory_region.h
> b/drivers/gpu/drm/i915/intel_memory_region.h
> index 3d8378c1b447..2214f251bec3 100644
> --- a/drivers/gpu/drm/i915/intel_memory_region.h
> +++ b/drivers/gpu/drm/i915/intel_memory_region.h
> @@ -127,6 +127,9 @@ int intel_memory_region_reserve(struct
> intel_memory_region *mem,
>  void intel_memory_region_debug(struct intel_memory_region *mr,
>                                struct drm_printer *printer);
>  
> +void intel_memory_region_avail(struct intel_memory_region *mr,
> +                              u64 *avail, u64 *visible_avail);
> +
>  struct intel_memory_region *
>  i915_gem_ttm_system_setup(struct drm_i915_private *i915,
>                           u16 type, u16 instance);
> diff --git a/include/uapi/drm/i915_drm.h
> b/include/uapi/drm/i915_drm.h
> index 7eacacb00373..e4847436bab8 100644
> --- a/include/uapi/drm/i915_drm.h
> +++ b/include/uapi/drm/i915_drm.h
> @@ -3228,7 +3228,15 @@ struct drm_i915_memory_region_info {
>          */
>         __u64 probed_size;
>  
> -       /** @unallocated_size: Estimate of memory remaining */
> +       /**
> +        * @unallocated_size: Estimate of memory remaining
> +        *
> +        * Requires CAP_PERFMON or CAP_SYS_ADMIN to get reliable
> accounting.
> +        * Without this (or if this is an older kernel) the value
> here will
> +        * always equal the @probed_size. Note this is only currently
> tracked
> +        * for I915_MEMORY_CLASS_DEVICE regions (for other types the
> value here
> +        * will always equal the @probed_size).
> +        */
>         __u64 unallocated_size;
>  
>         union {
> @@ -3262,6 +3270,27 @@ struct drm_i915_memory_region_info {
>                          * @probed_size.
>                          */
>                         __u64 probed_cpu_visible_size;
> +
> +                       /**
> +                        * @unallocated_cpu_visible_size: Estimate of
> CPU
> +                        * visible memory remaining.
> +                        *
> +                        * Note this is only tracked for
> +                        * I915_MEMORY_CLASS_DEVICE regions (for
> other types the
> +                        * value here will always equal the
> +                        * @probed_cpu_visible_size).
> +                        *
> +                        * Requires CAP_PERFMON or CAP_SYS_ADMIN to
> get reliable
> +                        * accounting.  Without this the value here
> will always
> +                        * equal the @probed_cpu_visible_size. Note
> this is only
> +                        * currently tracked for
> I915_MEMORY_CLASS_DEVICE
> +                        * regions (for other types the value here
> will also
> +                        * always equal the
> @probed_cpu_visible_size).
> +                        *
> +                        * If this is an older kernel the value here
> will be
> +                        * zero, see also @probed_cpu_visible_size.
> +                        */
> +                       __u64 unallocated_cpu_visible_size;
>                 };
>         };
>  };