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Add rtree lookup path caching.

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rtree-based extent lookups remain more expensive than chunk-based run
lookups, but with this optimization the fast path slowdown is ~3 CPU
cycles per metadata lookup (on Intel Core i7-4980HQ), versus ~11 cycles
prior.  The path caching speedup tends to degrade gracefully unless
allocated memory is spread far apart (as is the case when using a
mixture of sbrk() and mmap()).
This commit is contained in:
Jason Evans
2016-06-02 18:43:10 -07:00
parent 7be2ebc23f
commit 6f29a83924
7 changed files with 267 additions and 94 deletions
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3
src/rtree.c
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@@ -52,11 +52,12 @@ rtree_new(rtree_t *rtree, unsigned bits)
rtree->levels[height-1].cumbits = bits;
}
/* Compute lookup table to be used by rtree_start_level(). */
/* Compute lookup table to be used by rtree_[ctx_]start_level(). */
for (i = 0; i < RTREE_HEIGHT_MAX; i++) {
rtree->start_level[i] = hmin(RTREE_HEIGHT_MAX - 1 - i, height -
1);
}
rtree->start_level[RTREE_HEIGHT_MAX] = 0;
return (false);
}