| Message ID | 1456744394-29831-5-git-send-email-david.s.gordon@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 29/02/16 11:13, Dave Gordon wrote: > We're using this function for ringbuffers and other "small" objects, so > it's worth avoiding an extra malloc()/free() cycle if the page array is > small enough to put on the stack. Here we've chosen an arbitrary cutoff > of 32 (4k) pages, which is big enough for a ringbuffer (4 pages) or a > context image (currently up to 22 pages). > > v5: > change name of local array [Chris Wilson] > > Signed-off-by: Dave Gordon <david.s.gordon@intel.com> > Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> > Cc: Alex Dai <yu.dai@intel.com> > Cc: Chris Wilson <chris@chris-wilson.co.uk> > --- > drivers/gpu/drm/i915/i915_gem.c | 17 +++++++++++------ > 1 file changed, 11 insertions(+), 6 deletions(-) > > diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c > index c621b3e..c126211 100644 > --- a/drivers/gpu/drm/i915/i915_gem.c > +++ b/drivers/gpu/drm/i915/i915_gem.c > @@ -2417,7 +2417,8 @@ void *i915_gem_object_vmap_range(struct drm_i915_gem_object *obj, > unsigned int npages) > { > struct sg_page_iter sg_iter; > - struct page **pages; > + struct page *stack_pages[32]; > + struct page **pages = stack_pages; > void *addr; > int i; > > @@ -2426,10 +2427,13 @@ void *i915_gem_object_vmap_range(struct drm_i915_gem_object *obj, > return NULL; > } > > - pages = drm_malloc_gfp(npages, sizeof(*pages), GFP_TEMPORARY); > - if (pages == NULL) { > - DRM_DEBUG_DRIVER("Failed to get space for pages\n"); > - return NULL; > + if (npages > ARRAY_SIZE(stack_pages)) { > + /* Too big for stack -- allocate temporary array instead */ > + pages = drm_malloc_gfp(npages, sizeof(*pages), GFP_TEMPORARY); > + if (pages == NULL) { > + DRM_DEBUG_DRIVER("Failed to get space for pages\n"); > + return NULL; > + } > } > > i = 0; > @@ -2442,7 +2446,8 @@ void *i915_gem_object_vmap_range(struct drm_i915_gem_object *obj, > addr = vmap(pages, npages, 0, PAGE_KERNEL); > if (addr == NULL) > DRM_DEBUG_DRIVER("Failed to vmap pages\n"); > - drm_free_large(pages); > + if (pages != stack_pages) > + drm_free_large(pages); > > return addr; > } > Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Regards, Tvrtko
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index c621b3e..c126211 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -2417,7 +2417,8 @@ void *i915_gem_object_vmap_range(struct drm_i915_gem_object *obj, unsigned int npages) { struct sg_page_iter sg_iter; - struct page **pages; + struct page *stack_pages[32]; + struct page **pages = stack_pages; void *addr; int i; @@ -2426,10 +2427,13 @@ void *i915_gem_object_vmap_range(struct drm_i915_gem_object *obj, return NULL; } - pages = drm_malloc_gfp(npages, sizeof(*pages), GFP_TEMPORARY); - if (pages == NULL) { - DRM_DEBUG_DRIVER("Failed to get space for pages\n"); - return NULL; + if (npages > ARRAY_SIZE(stack_pages)) { + /* Too big for stack -- allocate temporary array instead */ + pages = drm_malloc_gfp(npages, sizeof(*pages), GFP_TEMPORARY); + if (pages == NULL) { + DRM_DEBUG_DRIVER("Failed to get space for pages\n"); + return NULL; + } } i = 0; @@ -2442,7 +2446,8 @@ void *i915_gem_object_vmap_range(struct drm_i915_gem_object *obj, addr = vmap(pages, npages, 0, PAGE_KERNEL); if (addr == NULL) DRM_DEBUG_DRIVER("Failed to vmap pages\n"); - drm_free_large(pages); + if (pages != stack_pages) + drm_free_large(pages); return addr; }
We're using this function for ringbuffers and other "small" objects, so it's worth avoiding an extra malloc()/free() cycle if the page array is small enough to put on the stack. Here we've chosen an arbitrary cutoff of 32 (4k) pages, which is big enough for a ringbuffer (4 pages) or a context image (currently up to 22 pages). v5: change name of local array [Chris Wilson] Signed-off-by: Dave Gordon <david.s.gordon@intel.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Cc: Alex Dai <yu.dai@intel.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> --- drivers/gpu/drm/i915/i915_gem.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-)