sna: Cap pwrite buffer alignment to 64k

We only want to create huge pwrite buffers when populating the inactive
cache for mmapped uploads. In the absence of using mmap for upload, be
more conservative with the alignment value so as not to simply waste
valuable aperture and memory.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

src/sna/kgem.c

@@ -2966,10 +2966,10 @@ struct kgem_bo *kgem_create_buffer(struct kgem *kgem,
 	}
 
 	/* Be a little more generous and hope to hold fewer mmappings */
-	alloc = ALIGN(size, kgem->partial_buffer_size);
 	bo = NULL;
 
 #if !DBG_NO_MAP_UPLOAD
+	alloc = ALIGN(size, kgem->partial_buffer_size);
 	if (kgem->has_cpu_bo) {
 		struct kgem_bo *old;
 
@@ -3084,6 +3084,8 @@ struct kgem_bo *kgem_create_buffer(struct kgem *kgem,
 			}
 		}
 	}
+#else
+	alloc = ALIGN(size, 64*1024);
 #endif
 
 	if (bo == NULL) {