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gpu: host1x: Memory context stealing

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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>
This commit is contained in:
Mikko Perttunen
2024-01-16 04:20:04 +02:00
committed by mobile promotions
parent 7e85d429e7
commit e062e9d49c
8 changed files with 318 additions and 45 deletions
Download Patch File Download Diff File Expand all files Collapse all files

48
drivers/gpu/host1x/include/linux/host1x-next.h
View File

@@ -495,12 +495,26 @@ int tegra_mipi_finish_calibration(struct tegra_mipi_device *device);
struct host1x_memory_context {
struct host1x *host;
refcount_t ref;
struct pid *owner;
struct device *dev; /* Owning engine */
struct pid *pid;
struct device dev;
u64 dma_mask;
u32 stream_id;
refcount_t ref;
struct host1x_hw_memory_context *hw;
struct device *context_dev; /* Context device */
struct list_head entry; /* Entry in hw_memory_context's list */
struct list_head mappings; /* List of mappings */
};
struct host1x_context_mapping {
struct host1x *host;
struct host1x_bo_mapping *mapping;
struct host1x_bo *bo;
enum dma_data_direction direction;
struct list_head entry;
};
#ifdef CONFIG_IOMMU_API
@@ -509,6 +523,11 @@ struct host1x_memory_context *host1x_memory_context_alloc(struct host1x *host1x,
struct pid *pid);
void host1x_memory_context_get(struct host1x_memory_context *cd);
void host1x_memory_context_put(struct host1x_memory_context *cd);
int host1x_memory_context_active(struct host1x_memory_context *cd);
void host1x_memory_context_inactive(struct host1x_memory_context *cd);
struct host1x_context_mapping *host1x_memory_context_map(
struct host1x_memory_context *ctx, struct host1x_bo *bo, enum dma_data_direction direction);
void host1x_memory_context_unmap(struct host1x_context_mapping *m);
#else
static inline struct host1x_memory_context *host1x_memory_context_alloc(struct host1x *host1x,
struct pid *pid)
@@ -523,6 +542,25 @@ static inline void host1x_memory_context_get(struct host1x_memory_context *cd)
static inline void host1x_memory_context_put(struct host1x_memory_context *cd)
{
}
static inline int host1x_memory_context_active(struct host1x_memory_context *cd)
{
return -ENODEV;
}
static inline void host1x_memory_context_inactive(struct host1x_memory_context *cd)
{
}
static inline struct host1x_context_mapping *host1x_memory_context_map(
struct host1x_memory_context *ctx, struct host1x_bo *bo, enum dma_data_direction direction)
{
return ERR_PTR(-ENODEV);
}
static inline void host1x_memory_context_unmap(struct host1x_context_mapping *m)
{
}
#endif
int host1x_actmon_read_avg_count(struct host1x_client *client);