Hi,
On 11/03/2024 10:06, Maíra Canal wrote:
Create a separate "tmpfs" kernel mount for V3D. This will allow us to
move away from the shmemfs `shm_mnt` and gives the flexibility to do
things like set our own mount options. Here, the interest is to use
"huge=", which should allow us to enable the use of THP for our
shmem-backed objects.
Signed-off-by: Maíra Canal <mcanal@xxxxxxxxxx>
---
drivers/gpu/drm/v3d/Makefile | 3 ++-
drivers/gpu/drm/v3d/v3d_drv.h | 9 +++++++
drivers/gpu/drm/v3d/v3d_gem.c | 3 +++
drivers/gpu/drm/v3d/v3d_gemfs.c | 46 +++++++++++++++++++++++++++++++++
4 files changed, 60 insertions(+), 1 deletion(-)
create mode 100644 drivers/gpu/drm/v3d/v3d_gemfs.c
diff --git a/drivers/gpu/drm/v3d/Makefile b/drivers/gpu/drm/v3d/Makefile
index b7d673f1153b..fcf710926057 100644
--- a/drivers/gpu/drm/v3d/Makefile
+++ b/drivers/gpu/drm/v3d/Makefile
@@ -13,7 +13,8 @@ v3d-y := \
v3d_trace_points.o \
v3d_sched.o \
v3d_sysfs.o \
- v3d_submit.o
+ v3d_submit.o \
+ v3d_gemfs.o
v3d-$(CONFIG_DEBUG_FS) += v3d_debugfs.o
diff --git a/drivers/gpu/drm/v3d/v3d_drv.h b/drivers/gpu/drm/v3d/v3d_drv.h
index 1950c723dde1..d2ce8222771a 100644
--- a/drivers/gpu/drm/v3d/v3d_drv.h
+++ b/drivers/gpu/drm/v3d/v3d_drv.h
@@ -119,6 +119,11 @@ struct v3d_dev {
struct drm_mm mm;
spinlock_t mm_lock;
+ /*
+ * tmpfs instance used for shmem backed objects
+ */
+ struct vfsmount *gemfs;
+
struct work_struct overflow_mem_work;
struct v3d_bin_job *bin_job;
@@ -519,6 +524,10 @@ void v3d_reset(struct v3d_dev *v3d);
void v3d_invalidate_caches(struct v3d_dev *v3d);
void v3d_clean_caches(struct v3d_dev *v3d);
+/* v3d_gemfs.c */
+void v3d_gemfs_init(struct v3d_dev *v3d);
+void v3d_gemfs_fini(struct v3d_dev *v3d);
+
/* v3d_submit.c */
void v3d_job_cleanup(struct v3d_job *job);
void v3d_job_put(struct v3d_job *job);
diff --git a/drivers/gpu/drm/v3d/v3d_gem.c b/drivers/gpu/drm/v3d/v3d_gem.c
index 66f4b78a6b2e..faefbe497e8d 100644
--- a/drivers/gpu/drm/v3d/v3d_gem.c
+++ b/drivers/gpu/drm/v3d/v3d_gem.c
@@ -287,6 +287,8 @@ v3d_gem_init(struct drm_device *dev)
v3d_init_hw_state(v3d);
v3d_mmu_set_page_table(v3d);
+ v3d_gemfs_init(v3d);
+
ret = v3d_sched_init(v3d);
if (ret) {
drm_mm_takedown(&v3d->mm);
@@ -304,6 +306,7 @@ v3d_gem_destroy(struct drm_device *dev)
struct v3d_dev *v3d = to_v3d_dev(dev);
v3d_sched_fini(v3d);
+ v3d_gemfs_fini(v3d);
/* Waiting for jobs to finish would need to be done before
* unregistering V3D.
diff --git a/drivers/gpu/drm/v3d/v3d_gemfs.c b/drivers/gpu/drm/v3d/v3d_gemfs.c
new file mode 100644
index 000000000000..8518b7da6f73
--- /dev/null
+++ b/drivers/gpu/drm/v3d/v3d_gemfs.c
@@ -0,0 +1,46 @@
+// SPDX-License-Identifier: GPL-2.0+
+/* Copyright (C) 2024 Raspberry Pi */
+
+#include <linux/fs.h>
+#include <linux/mount.h>
+
+#include "v3d_drv.h"
+
+void v3d_gemfs_init(struct v3d_dev *v3d)
+{
+ char huge_opt[] = "huge=always";
Using 'always' and not 'within_size' is deliberate? It can waste memory
but indeed could be best for performance. I am just asking and perhaps I
missed some prior discussion on this.
Regards,
Tvrtko
+ struct file_system_type *type;
+ struct vfsmount *gemfs;
+
+ /*
+ * By creating our own shmemfs mountpoint, we can pass in
+ * mount flags that better match our usecase. However, we
+ * only do so on platforms which benefit from it.
+ */
+ if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
+ goto err;
+
+ type = get_fs_type("tmpfs");
+ if (!type)
+ goto err;
+
+ gemfs = vfs_kern_mount(type, SB_KERNMOUNT, type->name, huge_opt);
+ if (IS_ERR(gemfs))
+ goto err;
+
+ v3d->gemfs = gemfs;
+ drm_info(&v3d->drm, "Using Transparent Hugepages\n");
+
+ return;
+
+err:
+ v3d->gemfs = NULL;
+ drm_notice(&v3d->drm,
+ "Transparent Hugepage support is recommended for optimal performance on this platform!\n");
+}
+
+void v3d_gemfs_fini(struct v3d_dev *v3d)
+{
+ if (v3d->gemfs)
+ kern_unmount(v3d->gemfs);
+}
--
2.43.0
