> -----Original Message-----
> From: Joonas Lahtinen [mailto:[email protected]]
> Sent: Monday, November 27, 2017 11:13 AM
> To: Intel graphics driver community testing & development <intel-
> [email protected]>
> Cc: Joonas Lahtinen <[email protected]>; Auld, Matthew
> <[email protected]>; Chris Wilson <[email protected]>; Jani
> Nikula <[email protected]>; Vivi, Rodrigo <[email protected]>;
> Rantala, Valtteri <[email protected]>; Tamminen, Eero T
> <[email protected]>
> Subject: [PATCH] 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 <[email protected]>
> Fixes: b901bb89324a ("drm/i915/gemfs: enable THP")
> Signed-off-by: Joonas Lahtinen <[email protected]>
> Cc: Matthew Auld <[email protected]>
> Cc: Chris Wilson <[email protected]>
> Cc: Jani Nikula <[email protected]>
> Cc: Rodrigo Vivi <[email protected]>
> Cc: Valtteri Rantala <[email protected]>
> Cc: Eero Tamminen <[email protected]>
> Reviewed-by: Chris Wilson <[email protected]>
> Reviewed-by: Matthew Auld <[email protected]>
Tested-by: Valtteri Rantala <[email protected]>
> ---
> drivers/gpu/drm/i915/i915_gemfs.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gemfs.c
> b/drivers/gpu/drm/i915/i915_gemfs.c
> index e2993857df37..888b7d3f04c3 100644
> --- a/drivers/gpu/drm/i915/i915_gemfs.c
> +++ b/drivers/gpu/drm/i915/i915_gemfs.c
> @@ -52,7 +52,8 @@ int i915_gemfs_init(struct drm_i915_private *i915)
>
> if (has_transparent_hugepage()) {
> struct super_block *sb = gemfs->mnt_sb;
> - char options[] = "huge=within_size";
> + /* FIXME: Disabled until we get W/A for read BW issue. */
> + char options[] = "huge=never";
> int flags = 0;
> int err;
>
> --
> 2.14.3
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