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hpfs: implement prefetch to improve performance

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This patch implements prefetch to improve performance.  It helps mostly
when scanning the bitmaps to calculate free space.

Signed-off-by: Mikulas Patocka <mpatocka@artax.karlin.mff.cuni.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mikulas Patocka
2013-07-04 19:04:01 +02:00
committed by Linus Torvalds
parent a0c1b75963
commit 275f495dbe
4 changed files with 63 additions and 5 deletions
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9
fs/hpfs/super.c
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@@ -121,7 +121,7 @@ unsigned hpfs_count_one_bitmap(struct super_block *s, secno secno)
unsigned long *bits;
unsigned count;
bits = hpfs_map_4sectors(s, secno, &qbh, 4);
bits = hpfs_map_4sectors(s, secno, &qbh, 0);
if (!bits)
return 0;
count = bitmap_weight(bits, 2048 * BITS_PER_BYTE);
@@ -134,8 +134,13 @@ static unsigned count_bitmaps(struct super_block *s)
unsigned n, count, n_bands;
n_bands = (hpfs_sb(s)->sb_fs_size + 0x3fff) >> 14;
count = 0;
for (n = 0; n < n_bands; n++)
for (n = 0; n < COUNT_RD_AHEAD; n++) {
hpfs_prefetch_bitmap(s, n);
}
for (n = 0; n < n_bands; n++) {
hpfs_prefetch_bitmap(s, n + COUNT_RD_AHEAD);
count += hpfs_count_one_bitmap(s, le32_to_cpu(hpfs_sb(s)->sb_bmp_dir[n]));
}
return count;
}