| Message ID | 20190906085214.11677-4-tzimmermann@suse.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Implement lazy unmapping for GEM VRAM buffers | expand |
> +void drm_gem_vram_bo_driver_move_notify(struct ttm_buffer_object *bo, > + bool evict, > + struct ttm_mem_reg *new_mem) > +{ [ ... ] > + if (!kmap->virtual) > + return; > + ttm_bo_kunmap(kmap); > + kmap->virtual = NULL; > +} I think ttm_buffer_object_destroy() needs "if (kmap->virtual) ttm_bo_kunmap()" too, due to the lazy unmap you can land there with an active mapping. cheers, Gerd
Hi Am 06.09.19 um 11:39 schrieb Gerd Hoffmann: >> +void drm_gem_vram_bo_driver_move_notify(struct ttm_buffer_object *bo, >> + bool evict, >> + struct ttm_mem_reg *new_mem) >> +{ > [ ... ] >> + if (!kmap->virtual) >> + return; >> + ttm_bo_kunmap(kmap); >> + kmap->virtual = NULL; >> +} > > I think ttm_buffer_object_destroy() needs "if (kmap->virtual) > ttm_bo_kunmap()" too, due to the lazy unmap you can land there > with an active mapping. Hmm, from my understanding, that final call to move_notify() is done by ttm_bo_cleanup_memtype_use(), which is called from within ttm_bo_put(). If we want to add a final kunmap, There's also the release_notify() callback, which is probably the right place to put it. Best regards Thomas > > cheers, > Gerd >
On Fri, Sep 06, 2019 at 12:37:47PM +0200, Thomas Zimmermann wrote: > Hi > > Am 06.09.19 um 11:39 schrieb Gerd Hoffmann: > >> +void drm_gem_vram_bo_driver_move_notify(struct ttm_buffer_object *bo, > >> + bool evict, > >> + struct ttm_mem_reg *new_mem) > >> +{ > > [ ... ] > >> + if (!kmap->virtual) > >> + return; > >> + ttm_bo_kunmap(kmap); > >> + kmap->virtual = NULL; > >> +} > > > > I think ttm_buffer_object_destroy() needs "if (kmap->virtual) > > ttm_bo_kunmap()" too, due to the lazy unmap you can land there > > with an active mapping. > > Hmm, from my understanding, that final call to move_notify() is done by > ttm_bo_cleanup_memtype_use(), which is called from within ttm_bo_put(). Ah, good, sounds like this should work indeed. Maybe add WARN_ON(kmap->virtual), just to be sure we don't overlooked something. cheers, Gerd
diff --git a/drivers/gpu/drm/drm_gem_vram_helper.c b/drivers/gpu/drm/drm_gem_vram_helper.c index 6c7912092876..973c703534d4 100644 --- a/drivers/gpu/drm/drm_gem_vram_helper.c +++ b/drivers/gpu/drm/drm_gem_vram_helper.c @@ -352,18 +352,17 @@ EXPORT_SYMBOL(drm_gem_vram_kmap); static void drm_gem_vram_kunmap_locked(struct drm_gem_vram_object *gbo) { - struct ttm_bo_kmap_obj *kmap = &gbo->kmap; - if (WARN_ON_ONCE(!gbo->kmap_use_count)) return; if (--gbo->kmap_use_count > 0) return; - if (!kmap->virtual) - return; - - ttm_bo_kunmap(kmap); - kmap->virtual = NULL; + /* + * Permanently mapping and unmapping buffers adds overhead from + * updating the page tables and creates debugging output. Therefore, + * we delay the actual unmap operation until the BO gets evicted + * from memory. See drm_gem_vram_bo_driver_move_notify(). + */ } /** @@ -489,6 +488,38 @@ int drm_gem_vram_bo_driver_verify_access(struct ttm_buffer_object *bo, } EXPORT_SYMBOL(drm_gem_vram_bo_driver_verify_access); +/** + * drm_gem_vram_bo_driver_move_notify() - + * Implements &struct ttm_bo_driver.move_notify + * @bo: TTM buffer object. Refers to &struct drm_gem_vram_object.bo + * @evict: True, if the BO is being evicted from graphics memory; + * false otherwise. + * @new_mem: New memory region, or NULL on destruction + */ +void drm_gem_vram_bo_driver_move_notify(struct ttm_buffer_object *bo, + bool evict, + struct ttm_mem_reg *new_mem) +{ + struct drm_gem_vram_object *gbo; + struct ttm_bo_kmap_obj *kmap; + + /* TTM may pass BOs that are not GEM VRAM BOs. */ + if (!drm_is_gem_vram(bo)) + return; + + gbo = drm_gem_vram_of_bo(bo); + kmap = &gbo->kmap; + + if (WARN_ON_ONCE(gbo->kmap_use_count)) + return; + + if (!kmap->virtual) + return; + ttm_bo_kunmap(kmap); + kmap->virtual = NULL; +} +EXPORT_SYMBOL(drm_gem_vram_bo_driver_move_notify); + /* * drm_gem_vram_mm_funcs - Functions for &struct drm_vram_mm * @@ -498,7 +529,8 @@ EXPORT_SYMBOL(drm_gem_vram_bo_driver_verify_access); */ const struct drm_vram_mm_funcs drm_gem_vram_mm_funcs = { .evict_flags = drm_gem_vram_bo_driver_evict_flags, - .verify_access = drm_gem_vram_bo_driver_verify_access + .verify_access = drm_gem_vram_bo_driver_verify_access, + .move_notify = drm_gem_vram_bo_driver_move_notify, }; EXPORT_SYMBOL(drm_gem_vram_mm_funcs); diff --git a/include/drm/drm_gem_vram_helper.h b/include/drm/drm_gem_vram_helper.h index 8c08bc87b788..e5ef0e4ab2e4 100644 --- a/include/drm/drm_gem_vram_helper.h +++ b/include/drm/drm_gem_vram_helper.h @@ -117,6 +117,10 @@ int drm_gem_vram_fill_create_dumb(struct drm_file *file, void drm_gem_vram_bo_driver_evict_flags(struct ttm_buffer_object *bo, struct ttm_placement *pl); +void drm_gem_vram_bo_driver_move_notify(struct ttm_buffer_object *bo, + bool evict, + struct ttm_mem_reg *new_mem); + int drm_gem_vram_bo_driver_verify_access(struct ttm_buffer_object *bo, struct file *filp);
Frequent mapping and unmapping a buffer object adds overhead for modifying the page table and creates debug output. Unmapping a buffer is only required when the memory manager evicts the buffer from its current location. Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> --- drivers/gpu/drm/drm_gem_vram_helper.c | 48 ++++++++++++++++++++++----- include/drm/drm_gem_vram_helper.h | 4 +++ 2 files changed, 44 insertions(+), 8 deletions(-)