dfadbbdb57
Sometimes we want to know whether a buffer is busy and wait for it (bo_wait). However, sometimes it would be more useful to be able to query whether a buffer is busy and being either read or written, and wait until it's stopped being either read or written. The point of this is to be able to avoid unnecessary waiting, e.g. if a GPU has written something to a buffer and is now reading that buffer, and a CPU wants to map that buffer for read, it needs to only wait for the last write. If there were no write, there wouldn't be any waiting needed. This, or course, requires user space drivers to send read/write flags with each relocation (like we have read/write domains in radeon, so we can actually use those for something useful now). Now how this patch works: The read/write flags should passed to ttm_validate_buffer. TTM maintains separate sync objects of the last read and write for each buffer, in addition to the sync object of the last use of a buffer. ttm_bo_wait then operates with one the sync objects. Signed-off-by: Marek Olšák <maraeo@gmail.com> Reviewed-by: Jerome Glisse <jglisse@redhat.com> Signed-off-by: Dave Airlie <airlied@redhat.com>
118 lines
4.3 KiB
C
118 lines
4.3 KiB
C
/**************************************************************************
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*
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* Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
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* All Rights Reserved.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sub license, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice (including the
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* next paragraph) shall be included in all copies or substantial portions
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* of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
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* THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
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* DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
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* OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
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* USE OR OTHER DEALINGS IN THE SOFTWARE.
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*
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**************************************************************************/
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/*
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* Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
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*/
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#ifndef _TTM_EXECBUF_UTIL_H_
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#define _TTM_EXECBUF_UTIL_H_
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#include "ttm/ttm_bo_api.h"
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#include <linux/list.h>
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/**
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* struct ttm_validate_buffer
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*
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* @head: list head for thread-private list.
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* @bo: refcounted buffer object pointer.
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* @new_sync_obj_arg: New sync_obj_arg for @bo, to be used once
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* adding a new sync object.
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* @usage Indicates how @bo is used by the device.
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* @reserved: Indicates whether @bo has been reserved for validation.
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* @removed: Indicates whether @bo has been removed from lru lists.
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* @put_count: Number of outstanding references on bo::list_kref.
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* @old_sync_obj: Pointer to a sync object about to be unreferenced
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* @old_sync_obj_read: Pointer to a read sync object about to be unreferenced.
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* @old_sync_obj_write: Pointer to a write sync object about to be unreferenced.
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*/
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struct ttm_validate_buffer {
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struct list_head head;
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struct ttm_buffer_object *bo;
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void *new_sync_obj_arg;
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enum ttm_buffer_usage usage;
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bool reserved;
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bool removed;
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int put_count;
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void *old_sync_obj;
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void *old_sync_obj_read;
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void *old_sync_obj_write;
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};
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/**
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* function ttm_eu_backoff_reservation
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*
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* @list: thread private list of ttm_validate_buffer structs.
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*
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* Undoes all buffer validation reservations for bos pointed to by
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* the list entries.
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*/
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extern void ttm_eu_backoff_reservation(struct list_head *list);
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/**
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* function ttm_eu_reserve_buffers
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*
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* @list: thread private list of ttm_validate_buffer structs.
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*
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* Tries to reserve bos pointed to by the list entries for validation.
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* If the function returns 0, all buffers are marked as "unfenced",
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* taken off the lru lists and are not synced for write CPU usage.
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*
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* If the function detects a deadlock due to multiple threads trying to
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* reserve the same buffers in reverse order, all threads except one will
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* back off and retry. This function may sleep while waiting for
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* CPU write reservations to be cleared, and for other threads to
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* unreserve their buffers.
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*
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* This function may return -ERESTART or -EAGAIN if the calling process
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* receives a signal while waiting. In that case, no buffers on the list
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* will be reserved upon return.
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*
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* Buffers reserved by this function should be unreserved by
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* a call to either ttm_eu_backoff_reservation() or
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* ttm_eu_fence_buffer_objects() when command submission is complete or
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* has failed.
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*/
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extern int ttm_eu_reserve_buffers(struct list_head *list);
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/**
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* function ttm_eu_fence_buffer_objects.
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*
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* @list: thread private list of ttm_validate_buffer structs.
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* @sync_obj: The new sync object for the buffers.
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*
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* This function should be called when command submission is complete, and
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* it will add a new sync object to bos pointed to by entries on @list.
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* It also unreserves all buffers, putting them on lru lists.
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*
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*/
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extern void ttm_eu_fence_buffer_objects(struct list_head *list, void *sync_obj);
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#endif
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