linux_dsm_epyc7002/drivers/gpu/drm
Chris Wilson a679f58d05 drm/i915: Flush pages on acquisition
When we return pages to the system, we ensure that they are marked as
being in the CPU domain since any external access is uncontrolled and we
must assume the worst. This means that we need to always flush the pages
on acquisition if we need to use them on the GPU, and from the beginning
have used set-domain. Set-domain is overkill for the purpose as it is a
general synchronisation barrier, but our intent is to only flush the
pages being swapped in. If we move that flush into the pages acquisition
phase, we know then that when we have obj->mm.pages, they are coherent
with the GPU and need only maintain that status without resorting to
heavy handed use of set-domain.

The principle knock-on effect for userspace is through mmap-gtt
pagefaulting. Our uAPI has always implied that the GTT mmap was async
(especially as when any pagefault occurs is unpredicatable to userspace)
and so userspace had to apply explicit domain control itself
(set-domain). However, swapping is transparent to the kernel, and so on
first fault we need to acquire the pages and make them coherent for
access through the GTT. Our use of set-domain here leaks into the uABI
that the first pagefault was synchronous. This is unintentional and
baring a few igt should be unoticed, nevertheless we bump the uABI
version for mmap-gtt to reflect the change in behaviour.

Another implication of the change is that gem_create() is presumed to
create an object that is coherent with the CPU and is in the CPU write
domain, so a set-domain(CPU) following a gem_create() would be a minor
operation that merely checked whether we could allocate all pages for
the object. On applying this change, a set-domain(CPU) causes a clflush
as we acquire the pages. This will have a small impact on mesa as we move
the clflush here on !llc from execbuf time to create, but that should
have minimal performance impact as the same clflush exists but is now
done early and because of the clflush issue, userspace recycles bo and
so should resist allocating fresh objects.

Internally, the presumption that objects are created in the CPU
write-domain and remain so through writes to obj->mm.mapping is more
prevalent than I expected; but easy enough to catch and apply a manual
flush.

For the future, we should push the page flush from the central
set_pages() into the callers so that we can more finely control when it
is applied, but for now doing it one location is easier to validate, at
the cost of sometimes flushing when there is no need.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.william.auld@gmail.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Antonio Argenziano <antonio.argenziano@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Matthew Auld <matthew.william.auld@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190321161908.8007-1-chris@chris-wilson.co.uk
2019-03-21 17:28:12 +00:00
..
amd drm/amd/display: Use vrr friendly pageflip throttling in DC. 2019-03-05 08:13:39 +10:00
arc
arm
armada
ast
atmel-hlcdc
bochs Linux 5.0 2019-03-04 12:02:55 +10:00
bridge
cirrus
etnaviv
exynos
fsl-dcu
gma500
hisilicon
i2c
i810
i915 drm/i915: Flush pages on acquisition 2019-03-21 17:28:12 +00:00
imx drm/imx: handle pending updates better, add plane zpos property support 2019-02-28 12:53:16 +10:00
lib
mediatek
meson
mga
mgag200
msm
mxsfb
nouveau
omapdrm
panel
pl111
qxl
r128
radeon Linux 5.0 2019-03-04 12:02:55 +10:00
rcar-du
rockchip
savage
scheduler Merge branch 'drm-next-5.1' of git://people.freedesktop.org/~agd5f/linux into drm-next 2019-02-22 15:56:42 +10:00
selftests
shmobile
sis
sti
stm
sun4i
tdfx
tegra
tilcdc
tinydrm
ttm
tve200
udl
v3d
vc4
vgem
via
virtio
vkms
vmwgfx
xen
zte
ati_pcigart.c
drm_agpsupport.c
drm_atomic_helper.c Linux 5.0 2019-03-04 12:02:55 +10:00
drm_atomic_state_helper.c
drm_atomic_uapi.c
drm_atomic.c
drm_auth.c
drm_blend.c
drm_bridge.c
drm_bufs.c
drm_cache.c
drm_client.c
drm_color_mgmt.c
drm_connector.c
drm_context.c
drm_crtc_helper_internal.h
drm_crtc_helper.c
drm_crtc_internal.h
drm_crtc.c
drm_damage_helper.c
drm_debugfs_crc.c
drm_debugfs.c
drm_dma.c
drm_dp_aux_dev.c
drm_dp_cec.c
drm_dp_dual_mode_helper.c
drm_dp_helper.c
drm_dp_mst_topology.c
drm_drv.c
drm_dsc.c
drm_dumb_buffers.c
drm_edid_load.c
drm_edid.c
drm_encoder_slave.c
drm_encoder.c
drm_fb_cma_helper.c
drm_fb_helper.c
drm_file.c drm-misc-fixes for v5.0: 2019-03-05 08:14:22 +10:00
drm_flip_work.c
drm_fourcc.c drm/fourcc: Add 64 bpp half float formats 2019-03-13 11:10:31 +01:00
drm_framebuffer.c
drm_gem_cma_helper.c
drm_gem_framebuffer_helper.c
drm_gem.c
drm_hashtab.c
drm_internal.h
drm_ioc32.c
drm_ioctl.c
drm_irq.c
drm_kms_helper_common.c
drm_lease.c
drm_legacy.h
drm_lock.c
drm_memory.c
drm_mipi_dsi.c
drm_mm.c
drm_mode_config.c
drm_mode_object.c
drm_modes.c
drm_modeset_helper.c
drm_modeset_lock.c
drm_of.c
drm_panel_orientation_quirks.c
drm_panel.c
drm_pci.c
drm_plane_helper.c
drm_plane.c
drm_prime.c
drm_print.c
drm_probe_helper.c
drm_property.c
drm_rect.c
drm_scatter.c
drm_scdc_helper.c
drm_simple_kms_helper.c
drm_syncobj.c
drm_sysfs.c
drm_trace_points.c
drm_trace.h
drm_vblank.c
drm_vm.c
drm_vma_manager.c
drm_writeback.c
Kconfig
Makefile