Re: [Intel-gfx] [PATCH 2/2] drm/i915: add back the avail tracking

[Matthew Auld <matthew.auld@intel.com>]

On 18/06/2021 14:44, Thomas Hellström wrote:
> 
> On 6/18/21 3:31 PM, Matthew Auld wrote:
>> Looks like it got lost along the way, so add it back. This is needed for
>> the region query uAPI where we need to report an accurate available size
>> for lmem.
> 
> Hmm. How is this uAPI intended to work in a multi-client environment 
> where the returned value can be nothing but a snapshot of the current 
> state, that can't be relied upon?

Ok, maybe I'm overselling it. s/accurate/current snapshot/. It does feel 
more useful than just returning -1 or so?

Daniel, Jason, any thoughts? Or maybe mr->total is all that real 
userspace really cares about?

> 
>> This time around let's push it directly into the allocator, which
>> simplifies things, like not having to care about internal fragmentation,
>> or having to remember to track things for all possible interfaces that
>> might want to allocate or reserve pages.
>>
>> Signed-off-by: Matthew Auld <matthew.auld@intel.com>
>> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
>> ---
>>   drivers/gpu/drm/i915/i915_buddy.c             |  6 ++++++
>>   drivers/gpu/drm/i915/i915_buddy.h             |  1 +
>>   drivers/gpu/drm/i915/i915_debugfs.c           |  5 +++--
>>   drivers/gpu/drm/i915/i915_query.c             |  2 +-
>>   drivers/gpu/drm/i915/i915_ttm_buddy_manager.c | 13 +++++++++++++
>>   drivers/gpu/drm/i915/i915_ttm_buddy_manager.h |  2 ++
>>   drivers/gpu/drm/i915/intel_memory_region.c    |  8 ++++++++
>>   drivers/gpu/drm/i915/intel_memory_region.h    |  4 ++++
>>   8 files changed, 38 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/i915_buddy.c 
>> b/drivers/gpu/drm/i915/i915_buddy.c
>> index 29dd7d0310c1..27cd2487a18f 100644
>> --- a/drivers/gpu/drm/i915/i915_buddy.c
>> +++ b/drivers/gpu/drm/i915/i915_buddy.c
>> @@ -80,6 +80,7 @@ int i915_buddy_init(struct i915_buddy_mm *mm, u64 
>> size, u64 chunk_size)
>>       size = round_down(size, chunk_size);
>>       mm->size = size;
>> +    mm->avail = size;
>>       mm->chunk_size = chunk_size;
>>       mm->max_order = ilog2(size) - ilog2(chunk_size);
>> @@ -159,6 +160,8 @@ void i915_buddy_fini(struct i915_buddy_mm *mm)
>>           i915_block_free(mm, mm->roots[i]);
>>       }
>> +    GEM_WARN_ON(mm->avail != mm->size);
>> +
>>       kfree(mm->roots);
>>       kfree(mm->free_list);
>>       kmem_cache_destroy(mm->slab_blocks);
>> @@ -235,6 +238,7 @@ void i915_buddy_free(struct i915_buddy_mm *mm,
>>                struct i915_buddy_block *block)
>>   {
>>       GEM_BUG_ON(!i915_buddy_block_is_allocated(block));
>> +    mm->avail += i915_buddy_block_size(mm, block);
>>       __i915_buddy_free(mm, block);
>>   }
>> @@ -288,6 +292,7 @@ i915_buddy_alloc(struct i915_buddy_mm *mm, 
>> unsigned int order)
>>       }
>>       mark_allocated(block);
>> +    mm->avail -= i915_buddy_block_size(mm, block);
>>       kmemleak_update_trace(block);
>>       return block;
>> @@ -373,6 +378,7 @@ int i915_buddy_alloc_range(struct i915_buddy_mm *mm,
>>               }
>>               mark_allocated(block);
>> +            mm->avail -= i915_buddy_block_size(mm, block);
>>               list_add_tail(&block->link, &allocated);
>>               continue;
>>           }
>> diff --git a/drivers/gpu/drm/i915/i915_buddy.h 
>> b/drivers/gpu/drm/i915/i915_buddy.h
>> index 37f8c42071d1..feb7c1bb6244 100644
>> --- a/drivers/gpu/drm/i915/i915_buddy.h
>> +++ b/drivers/gpu/drm/i915/i915_buddy.h
>> @@ -70,6 +70,7 @@ struct i915_buddy_mm {
>>       /* Must be at least PAGE_SIZE */
>>       u64 chunk_size;
>>       u64 size;
>> +    u64 avail;
>>   };
>>   static inline u64
>> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c 
>> b/drivers/gpu/drm/i915/i915_debugfs.c
>> index cc745751ac53..4765f220469e 100644
>> --- a/drivers/gpu/drm/i915/i915_debugfs.c
>> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
>> @@ -246,8 +246,9 @@ static int i915_gem_object_info(struct seq_file 
>> *m, void *data)
>>              atomic_read(&i915->mm.free_count),
>>              i915->mm.shrink_memory);
>>       for_each_memory_region(mr, i915, id)
>> -        seq_printf(m, "%s: total:%pa, available:%pa bytes\n",
>> -               mr->name, &mr->total, &mr->avail);
>> +        seq_printf(m, "%s: total:%pa, available:%llu bytes\n",
>> +               mr->name, &mr->total,
>> +               intel_memory_region_get_avail(mr));
>>       return 0;
>>   }
>> diff --git a/drivers/gpu/drm/i915/i915_query.c 
>> b/drivers/gpu/drm/i915/i915_query.c
>> index e49da36c62fb..f10dcea94ac9 100644
>> --- a/drivers/gpu/drm/i915/i915_query.c
>> +++ b/drivers/gpu/drm/i915/i915_query.c
>> @@ -465,7 +465,7 @@ static int query_memregion_info(struct 
>> drm_i915_private *i915,
>>           info.region.memory_class = mr->type;
>>           info.region.memory_instance = mr->instance;
>>           info.probed_size = mr->total;
>> -        info.unallocated_size = mr->avail;
>> +        info.unallocated_size = intel_memory_region_get_avail(mr);
>>           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 fc7ad5c035b8..562d11edc5e4 100644
>> --- a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
>> +++ b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
>> @@ -246,3 +246,16 @@ int i915_ttm_buddy_man_reserve(struct 
>> ttm_resource_manager *man,
>>       return ret;
>>   }
>> +/**
>> + * i915_ttm_buddy_man_avail - Get the currently available size
>> + * @man: The buddy allocator ttm manager
>> + *
>> + * Return: The available size in bytes
>> + */
>> +u64 i915_ttm_buddy_man_get_avail(struct ttm_resource_manager *man)
>> +{
>> +    struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);
>> +    struct i915_buddy_mm *mm = &bman->mm;
>> +
>> +    return mm->avail;
>> +}
>> diff --git a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.h 
>> b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.h
>> index 26026213e20a..39f5b1a4c3e7 100644
>> --- a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.h
>> +++ b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.h
>> @@ -53,4 +53,6 @@ int i915_ttm_buddy_man_fini(struct ttm_device *bdev,
>>   int i915_ttm_buddy_man_reserve(struct ttm_resource_manager *man,
>>                      u64 start, u64 size);
>> +u64 i915_ttm_buddy_man_get_avail(struct ttm_resource_manager *man);
>> +
>>   #endif
>> diff --git a/drivers/gpu/drm/i915/intel_memory_region.c 
>> b/drivers/gpu/drm/i915/intel_memory_region.c
>> index df59f884d37c..269cbb60e233 100644
>> --- a/drivers/gpu/drm/i915/intel_memory_region.c
>> +++ b/drivers/gpu/drm/i915/intel_memory_region.c
>> @@ -132,6 +132,14 @@ void intel_memory_region_set_name(struct 
>> intel_memory_region *mem,
>>       va_end(ap);
>>   }
>> +u64 intel_memory_region_get_avail(struct intel_memory_region *mr)
>> +{
>> +    if (mr->type == INTEL_MEMORY_LOCAL)
>> +        return i915_ttm_buddy_man_get_avail(mr->region_private);
>> +
>> +    return mr->avail;
>> +}
> 
> Perhaps a kerneldoc comment here as well?
> 
> 
>> +
>>   static void __intel_memory_region_destroy(struct kref *kref)
>>   {
>>       struct intel_memory_region *mem =
>> diff --git a/drivers/gpu/drm/i915/intel_memory_region.h 
>> b/drivers/gpu/drm/i915/intel_memory_region.h
>> index 2be8433d373a..6f7a073d5a70 100644
>> --- a/drivers/gpu/drm/i915/intel_memory_region.h
>> +++ b/drivers/gpu/drm/i915/intel_memory_region.h
>> @@ -74,6 +74,7 @@ struct intel_memory_region {
>>       resource_size_t io_start;
>>       resource_size_t min_page_size;
>>       resource_size_t total;
>> +    /* Do not access directly. Use the accessor instead. */
>>       resource_size_t avail;
>>       u16 type;
>> @@ -125,4 +126,7 @@ intel_memory_region_set_name(struct 
>> intel_memory_region *mem,
>>   int intel_memory_region_reserve(struct intel_memory_region *mem,
>>                   resource_size_t offset,
>>                   resource_size_t size);
>> +
>> +u64 intel_memory_region_get_avail(struct intel_memory_region *mem);
>> +
>>   #endif
> 
> Otherwise code itself looks good to me.
> 
> Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> 
> 
> 
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