drm/i915/gemfs: enable THP

Enable transparent-huge-pages through gemfs by mounting with
huge=within_size.

v2: sprinkle within_size comment

Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171006145041.21673-4-matthew.auld@intel.com
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20171006221833.32439-3-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/i915_gemfs.c b/drivers/gpu/drm/i915/i915_gemfs.c
index 168d0bd98f603615bc99b09fda36a582d0bb3785..e2993857df37bb365225f2dcf1797d389ae73fb4 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gemfs.c
+++ b/drivers/gpu/drm/i915/i915_gemfs.c
@@ -24,6 +24,7 @@
 
 #include <linux/fs.h>
 #include <linux/mount.h>
+#include <linux/pagemap.h>
 
 #include "i915_drv.h"
 #include "i915_gemfs.h"
@@ -41,6 +42,27 @@ int i915_gemfs_init(struct drm_i915_private *i915)
        if (IS_ERR(gemfs))
                return PTR_ERR(gemfs);
 
+       /*
+        * Enable huge-pages for objects that are at least HPAGE_PMD_SIZE, most
+        * likely 2M. Note that within_size may overallocate huge-pages, if say
+        * we allocate an object of size 2M + 4K, we may get 2M + 2M, but under
+        * memory pressure shmem should split any huge-pages which can be
+        * shrunk.
+        */
+
+       if (has_transparent_hugepage()) {
+               struct super_block *sb = gemfs->mnt_sb;
+               char options[] = "huge=within_size";
+               int flags = 0;
+               int err;
+
+               err = sb->s_op->remount_fs(sb, &flags, options);
+               if (err) {
+                       kern_unmount(gemfs);
+                       return err;
+               }
+       }
+
        i915->mm.gemfs = gemfs;
 
        return 0;