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We need to keep the default context state around to instantiate new contexts (aka golden rendercontext), and we also keep it pinned while the engine is active so that we can quickly reset a hanging context. However, the default contexts are large enough to merit keeping in swappable memory as opposed to kernel memory, so we store them inside shmemfs. Currently, we use the normal GEM objects to create the default context image, but we can throw away all but the shmemfs file. This greatly simplifies the tricky power management code which wants to run underneath the normal GT locking, and we definitely do not want to use any high level objects that may appear to recurse back into the GT. Though perhaps the primary advantage of the complex GEM object is that we aggressively cache the mapping, but here we are recreating the vm_area everytime time we unpark. At the worst, we add a lightweight cache, but first find a microbenchmark that is impacted. Having started to create some utility functions to make working with shmemfs objects easier, we can start putting them to wider use, where GEM objects are overkill, such as storing persistent error state. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Matthew Auld <matthew.auld@intel.com> Cc: Ramalingam C <ramalingam.c@intel.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Reviewed-by: Matthew Auld <matthew.auld@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20200429172429.6054-1-chris@chris-wilson.co.uk
23 lines
609 B
C
23 lines
609 B
C
/* SPDX-License-Identifier: MIT */
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/*
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* Copyright © 2020 Intel Corporation
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*/
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#ifndef SHMEM_UTILS_H
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#define SHMEM_UTILS_H
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#include <linux/types.h>
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struct drm_i915_gem_object;
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struct file;
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struct file *shmem_create_from_data(const char *name, void *data, size_t len);
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struct file *shmem_create_from_object(struct drm_i915_gem_object *obj);
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void *shmem_pin_map(struct file *file);
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void shmem_unpin_map(struct file *file, void *ptr);
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int shmem_read(struct file *file, loff_t off, void *dst, size_t len);
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int shmem_write(struct file *file, loff_t off, void *src, size_t len);
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#endif /* SHMEM_UTILS_H */
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