Files
linux-nv-oot/drivers/gpu/drm/tegra/uapi.h
Mikko Perttunen 276418c013 gpu: host1x: Memory context stealing
Currently, each process holding an open TegraDRM channel reserves
for itself one of the limited number of hardware memory contexts.
Attempting to allocate a channel when all contexts are in use
results in failure.

While we cannot have more contexts than the hardware supports in
active use, idle channels don't necessarily need to have a backing
memory context. As such, in this patch, we add another layer
to allow hardware memory contexts to be "stolen away" by channels
that are in active use, from idle processes.

The way this is implemented, is by keeping track of memory
mappings on each abstracted memory context. If we need to
steal that memory context's backing hardware context, we unmap
everything from it and give it away. When that abstracted
memory context is needed again (re-activated), we attempt
to allocate or steal another hardware context and re-map
the previously unmapped buffers.

Unfortunately, this means additional overhead and unpredictability
at submit time. Submit can fail if we cannot re-allocate a
backing memory context. Future work includes a provision for
un-stealable backing hardware memory contexts for processes
requiring more determinism, as well as optimization and cosmetic
improvements.

Bug 4403250
Bug 4399310

Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
Change-Id: I3d13e3476f1bff3c4757152254496cddaaafd76a
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nv-oot/+/3058905
Reviewed-by: Santosh BS <santoshb@nvidia.com>
GVS: Gerrit_Virtual_Submit <buildbot_gerritrpt@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nv-oot/+/3227749
GVS: buildbot_gerritrpt <buildbot_gerritrpt@nvidia.com>
Tested-by: Dane Liu <danel@nvidia.com>
Reviewed-by: Bibek Basu <bbasu@nvidia.com>
2024-11-13 20:55:08 -08:00

59 lines
1.6 KiB
C

/* SPDX-License-Identifier: GPL-2.0-only */
/* Copyright (c) 2020 NVIDIA Corporation */
#ifndef _TEGRA_DRM_UAPI_H
#define _TEGRA_DRM_UAPI_H
#include <linux/dma-mapping.h>
#include <linux/idr.h>
#include <linux/kref.h>
#include <linux/xarray.h>
#include <drm/drm.h>
struct drm_file;
struct drm_device;
struct tegra_drm_file {
/* Legacy UAPI state */
struct idr legacy_contexts;
struct mutex lock;
/* New UAPI state */
struct xarray contexts;
struct xarray syncpoints;
};
struct tegra_drm_mapping {
struct kref ref;
struct host1x_bo_mapping *bo_map;
struct host1x_context_mapping *ctx_map;
struct host1x_bo *bo;
dma_addr_t iova;
dma_addr_t iova_end;
};
int tegra_drm_ioctl_channel_open(struct drm_device *drm, void *data,
struct drm_file *file);
int tegra_drm_ioctl_channel_close(struct drm_device *drm, void *data,
struct drm_file *file);
int tegra_drm_ioctl_channel_map(struct drm_device *drm, void *data,
struct drm_file *file);
int tegra_drm_ioctl_channel_unmap(struct drm_device *drm, void *data,
struct drm_file *file);
int tegra_drm_ioctl_channel_submit(struct drm_device *drm, void *data,
struct drm_file *file);
int tegra_drm_ioctl_syncpoint_allocate(struct drm_device *drm, void *data,
struct drm_file *file);
int tegra_drm_ioctl_syncpoint_free(struct drm_device *drm, void *data,
struct drm_file *file);
int tegra_drm_ioctl_syncpoint_wait(struct drm_device *drm, void *data,
struct drm_file *file);
void tegra_drm_uapi_close_file(struct tegra_drm_file *file);
void tegra_drm_mapping_put(struct tegra_drm_mapping *mapping);
#endif