i915_gemfs.c

 1// SPDX-License-Identifier: MIT
 2/*
 3 * Copyright © 2017 Intel Corporation
 4 */
 5
 6#include <linux/fs.h>
 7#include <linux/mount.h>
 8#include <linux/fs_context.h>
 9
10#include <drm/drm_print.h>
11
12#include "i915_drv.h"
13#include "i915_gemfs.h"
14#include "i915_utils.h"
15
16void i915_gemfs_init(struct drm_i915_private *i915)
17{
18	struct file_system_type *type;
19	struct fs_context *fc;
20	struct vfsmount *gemfs;
21	int ret;
22
23	/*
24	 * By creating our own shmemfs mountpoint, we can pass in
25	 * mount flags that better match our usecase.
26	 *
27	 * One example, although it is probably better with a per-file
28	 * control, is selecting huge page allocations ("huge=within_size").
29	 * However, we only do so on platforms which benefit from it, or to
30	 * offset the overhead of iommu lookups, where with latter it is a net
31	 * win even on platforms which would otherwise see some performance
32	 * regressions such a slow reads issue on Broadwell and Skylake.
33	 */
34
35	if (GRAPHICS_VER(i915) < 11 && !i915_vtd_active(i915))
36		return;
37
38	if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
39		goto err;
40
41	type = get_fs_type("tmpfs");
42	if (!type)
43		goto err;
44
45	fc = fs_context_for_mount(type, SB_KERNMOUNT);
46	if (IS_ERR(fc))
47		goto err;
48	ret = vfs_parse_fs_string(fc, "source", "tmpfs");
49	if (!ret)
50		ret = vfs_parse_fs_string(fc, "huge", "within_size");
51	if (!ret)
52		gemfs = fc_mount_longterm(fc);
53	put_fs_context(fc);
54	if (ret)
55		goto err;
56
57	i915->mm.gemfs = gemfs;
58	drm_info(&i915->drm, "Using Transparent Hugepages\n");
59	return;
60
61err:
62	drm_notice(&i915->drm,
63		   "Transparent Hugepage support is recommended for optimal performance%s\n",
64		   GRAPHICS_VER(i915) >= 11 ? " on this platform!" :
65					      " when IOMMU is enabled!");
66}
67
68void i915_gemfs_fini(struct drm_i915_private *i915)
69{
70	kern_unmount(i915->mm.gemfs);
71}