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intel/perf: make oa_sample_buffers private

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All references to this data structure have been moved inside the perf
subsystem.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
This commit is contained in:
Mark Janes
2019-07-10 14:25:47 -07:00
parent f2a049b4e3
commit be8b466cff
2 changed files with 120 additions and 119 deletions
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120
src/intel/perf/gen_perf.c
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@@ -69,6 +69,126 @@
#define MAP_READ (1 << 0)
#define MAP_WRITE (1 << 1)
/**
* Periodic OA samples are read() into these buffer structures via the
* i915 perf kernel interface and appended to the
* perf_ctx->sample_buffers linked list. When we process the
* results of an OA metrics query we need to consider all the periodic
* samples between the Begin and End MI_REPORT_PERF_COUNT command
* markers.
*
* 'Periodic' is a simplification as there are other automatic reports
* written by the hardware also buffered here.
*
* Considering three queries, A, B and C:
*
* Time ---->
* ________________A_________________
* | |
* | ________B_________ _____C___________
* | | | | | |
*
* And an illustration of sample buffers read over this time frame:
* [HEAD ][ ][ ][ ][ ][ ][ ][ ][TAIL ]
*
* These nodes may hold samples for query A:
* [ ][ ][ A ][ A ][ A ][ A ][ A ][ ][ ]
*
* These nodes may hold samples for query B:
* [ ][ ][ B ][ B ][ B ][ ][ ][ ][ ]
*
* These nodes may hold samples for query C:
* [ ][ ][ ][ ][ ][ C ][ C ][ C ][ ]
*
* The illustration assumes we have an even distribution of periodic
* samples so all nodes have the same size plotted against time:
*
* Note, to simplify code, the list is never empty.
*
* With overlapping queries we can see that periodic OA reports may
* relate to multiple queries and care needs to be take to keep
* track of sample buffers until there are no queries that might
* depend on their contents.
*
* We use a node ref counting system where a reference ensures that a
* node and all following nodes can't be freed/recycled until the
* reference drops to zero.
*
* E.g. with a ref of one here:
* [ 0 ][ 0 ][ 1 ][ 0 ][ 0 ][ 0 ][ 0 ][ 0 ][ 0 ]
*
* These nodes could be freed or recycled ("reaped"):
* [ 0 ][ 0 ]
*
* These must be preserved until the leading ref drops to zero:
* [ 1 ][ 0 ][ 0 ][ 0 ][ 0 ][ 0 ][ 0 ]
*
* When a query starts we take a reference on the current tail of
* the list, knowing that no already-buffered samples can possibly
* relate to the newly-started query. A pointer to this node is
* also saved in the query object's ->oa.samples_head.
*
* E.g. starting query A while there are two nodes in .sample_buffers:
* ________________A________
* |
*
* [ 0 ][ 1 ]
* ^_______ Add a reference and store pointer to node in
* A->oa.samples_head
*
* Moving forward to when the B query starts with no new buffer nodes:
* (for reference, i915 perf reads() are only done when queries finish)
* ________________A_______
* | ________B___
* | |
*
* [ 0 ][ 2 ]
* ^_______ Add a reference and store pointer to
* node in B->oa.samples_head
*
* Once a query is finished, after an OA query has become 'Ready',
* once the End OA report has landed and after we we have processed
* all the intermediate periodic samples then we drop the
* ->oa.samples_head reference we took at the start.
*
* So when the B query has finished we have:
* ________________A________
* | ______B___________
* | | |
* [ 0 ][ 1 ][ 0 ][ 0 ][ 0 ]
* ^_______ Drop B->oa.samples_head reference
*
* We still can't free these due to the A->oa.samples_head ref:
* [ 1 ][ 0 ][ 0 ][ 0 ]
*
* When the A query finishes: (note there's a new ref for C's samples_head)
* ________________A_________________
* | |
* | _____C_________
* | | |
* [ 0 ][ 0 ][ 0 ][ 0 ][ 1 ][ 0 ][ 0 ]
* ^_______ Drop A->oa.samples_head reference
*
* And we can now reap these nodes up to the C->oa.samples_head:
* [ X ][ X ][ X ][ X ]
* keeping -> [ 1 ][ 0 ][ 0 ]
*
* We reap old sample buffers each time we finish processing an OA
* query by iterating the sample_buffers list from the head until we
* find a referenced node and stop.
*
* Reaped buffers move to a perfquery.free_sample_buffers list and
* when we come to read() we first look to recycle a buffer from the
* free_sample_buffers list before allocating a new buffer.
*/
struct oa_sample_buf {
struct exec_node link;
int refcount;
int len;
uint8_t buf[I915_PERF_OA_SAMPLE_SIZE * 10];
uint32_t last_timestamp;
};
struct gen_perf_query_object *
gen_perf_new_query(struct gen_perf_context *perf_ctx, unsigned query_index)
{