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libext2fs: further optimize rb_test_bit 

Profiling shows that rb_test_bit() is now calling ext2fs_rb_next() a
lot, and this function is now the hot spot when running e2freefrag.
If we cache the results of ext2fs_rb_next(), we can eliminate those
extra calls, which further speeds up both e2freefrag and e2fsck by
reducing the amount of CPU time spent in userspace.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
bitmap-optimize
Theodore Ts'o 2012-10-05 21:59:40 -04:00
parent 0bcba36f3f
commit fb129bba73
1 changed files with 19 additions and 4 deletions
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23
lib/ext2fs/blkmap64_rb.c
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@ -40,6 +40,7 @@ struct ext2fs_rb_private {
struct rb_root root;
struct bmap_rb_extent *wcursor;
struct bmap_rb_extent *rcursor;
struct bmap_rb_extent *rcursor_next;
#ifdef BMAP_STATS_OPS
__u64 mark_hit;
__u64 test_hit;
@ -152,6 +153,8 @@ static void rb_free_extent(struct ext2fs_rb_private *bp,
bp->wcursor = NULL;
if (bp->rcursor == ext)
bp->rcursor = NULL;
if (bp->rcursor_next == ext)
bp->rcursor_next = NULL;
ext2fs_free_mem(&ext);
}
@ -166,6 +169,7 @@ static errcode_t rb_alloc_private_data (ext2fs_generic_bitmap bitmap)
bp->root = RB_ROOT;
bp->rcursor = NULL;
bp->rcursor_next = NULL;
bp->wcursor = NULL;
#ifdef BMAP_STATS_OPS
@ -306,7 +310,7 @@ static errcode_t rb_resize_bmap(ext2fs_generic_bitmap bmap,
inline static int
rb_test_bit(struct ext2fs_rb_private *bp, __u64 bit)
{
struct bmap_rb_extent *rcursor, *next_ext;
struct bmap_rb_extent *rcursor, *next_ext = NULL;
struct rb_node *parent = NULL, *next;
struct rb_node **n = &bp->root.rb_node;
struct bmap_rb_extent *ext;
@ -322,9 +326,15 @@ rb_test_bit(struct ext2fs_rb_private *bp, __u64 bit)
return 1;
}
next = ext2fs_rb_next(&rcursor->node);
if (next) {
next_ext = ext2fs_rb_entry(next, struct bmap_rb_extent, node);
next_ext = bp->rcursor_next;
if (!next_ext) {
next = ext2fs_rb_next(&rcursor->node);
if (next)
next_ext = ext2fs_rb_entry(next, struct bmap_rb_extent,
node);
bp->rcursor_next = next_ext;
}
if (next_ext) {
if ((bit >= rcursor->start + rcursor->count) &&
(bit < next_ext->start)) {
#ifdef BMAP_STATS_OPS
@ -333,6 +343,8 @@ rb_test_bit(struct ext2fs_rb_private *bp, __u64 bit)
return 0;
}
}
bp->rcursor = NULL;
bp->rcursor_next = NULL;
rcursor = bp->wcursor;
if (!rcursor)
@ -352,6 +364,7 @@ search_tree:
n = &(*n)->rb_right;
else {
bp->rcursor = ext;
bp->rcursor_next = NULL;
return 1;
}
}
@ -368,6 +381,7 @@ static int rb_insert_extent(__u64 start, __u64 count,
struct bmap_rb_extent *ext;
int retval = 0;
bp->rcursor_next = NULL;
ext = bp->wcursor;
if (ext) {
if (start >= ext->start &&
@ -738,6 +752,7 @@ static void rb_clear_bmap(ext2fs_generic_bitmap bitmap)
rb_free_tree(&bp->root);
bp->rcursor = NULL;
bp->rcursor_next = NULL;
bp->wcursor = NULL;
}