drm/i915: mark pwrite/pread slowpaths with unlikely

Beside helping the compiler untangle this maze they double-up as
documentation for which parts of the code aren't performance-critical
but just around to keep old (but already dead-slow) userspace from
breaking.

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index c964dfb..b8c6248 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -298,7 +298,7 @@ shmem_pread_fast(struct page *page, int shmem_page_offset, int page_length,
        char *vaddr;
        int ret;
 
-       if (page_do_bit17_swizzling)
+       if (unlikely(page_do_bit17_swizzling))
                return -EINVAL;
 
        vaddr = kmap_atomic(page);
@@ -317,7 +317,7 @@ static void
 shmem_clflush_swizzled_range(char *addr, unsigned long length,
                             bool swizzled)
 {
-       if (swizzled) {
+       if (unlikely(swizzled)) {
                unsigned long start = (unsigned long) addr;
                unsigned long end = (unsigned long) addr + length;
 
@@ -629,7 +629,7 @@ shmem_pwrite_fast(struct page *page, int shmem_page_offset, int page_length,
        char *vaddr;
        int ret;
 
-       if (page_do_bit17_swizzling)
+       if (unlikely(page_do_bit17_swizzling))
                return -EINVAL;
 
        vaddr = kmap_atomic(page);
@@ -660,7 +660,7 @@ shmem_pwrite_slow(struct page *page, int shmem_page_offset, int page_length,
        int ret;
 
        vaddr = kmap(page);
-       if (needs_clflush_before || page_do_bit17_swizzling)
+       if (unlikely(needs_clflush_before || page_do_bit17_swizzling))
                shmem_clflush_swizzled_range(vaddr + shmem_page_offset,
                                             page_length,
                                             page_do_bit17_swizzling);