linux/drivers/gpu/drm/i915/i915_gemfs.c
Joonas Lahtinen 9987da4b5d drm/i915: Disable THP until we have a GPU read BW W/A
We seem to be missing some W/A for 2M pages and are getting
a hit on raw GPU read bandwidths (even 30%) even though the
GPU write bandwidths improve (even 10%).

For now, disable THP, which is our only practical source of
2M pages until we have a W/A for the issue.

v2:
- Be explicit that we talk about GPU bandwidths (Eero)
- s/deny/never/ because that's why (Chris)

Reported-by: Valtteri Rantala <valtteri.rantala@intel.com>
Fixes: b901bb8932 ("drm/i915/gemfs: enable THP")
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Valtteri Rantala <valtteri.rantala@intel.com>
Cc: Eero Tamminen <eero.t.tamminen@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Tested-by: Valtteri Rantala <valtteri.rantala@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171127091233.7001-1-joonas.lahtinen@linux.intel.com
2017-11-29 09:54:59 +02:00

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C

/*
* Copyright © 2017 Intel Corporation
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* The above copyright notice and this permission notice (including the next
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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*/
#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/pagemap.h>
#include "i915_drv.h"
#include "i915_gemfs.h"
int i915_gemfs_init(struct drm_i915_private *i915)
{
struct file_system_type *type;
struct vfsmount *gemfs;
type = get_fs_type("tmpfs");
if (!type)
return -ENODEV;
gemfs = kern_mount(type);
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;
/* FIXME: Disabled until we get W/A for read BW issue. */
char options[] = "huge=never";
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;
}
void i915_gemfs_fini(struct drm_i915_private *i915)
{
kern_unmount(i915->mm.gemfs);
}