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Slight optimization for the standard case of rotdelay=0.

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This commit is contained in:
David Greenman 1995-09-08 17:16:32 +00:00
parent 1c6d84074a
commit 9eda220c0b
1 changed files with 11 additions and 11 deletions
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22
sys/ufs/ffs/ffs_alloc.c
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@ -31,7 +31,7 @@
* SUCH DAMAGE.
*
* @(#)ffs_alloc.c 8.8 (Berkeley) 2/21/94
* $Id: ffs_alloc.c,v 1.15 1995/08/07 08:16:32 davidg Exp $
* $Id: ffs_alloc.c,v 1.16 1995/08/25 19:40:26 bde Exp $
*/
#include <sys/param.h>
@ -655,18 +655,18 @@ ffs_blkpref(ip, lbn, indx, bap)
* requested rotationally delayed by fs_rotdelay milliseconds.
*/
nextblk = bap[indx - 1] + fs->fs_frag;
if (indx < fs->fs_maxcontig || bap[indx - fs->fs_maxcontig] +
if (fs->fs_rotdelay == 0 || indx < fs->fs_maxcontig ||
bap[indx - fs->fs_maxcontig] +
blkstofrags(fs, fs->fs_maxcontig) != nextblk)
return (nextblk);
if (fs->fs_rotdelay != 0)
/*
* Here we convert ms of delay to frags as:
* (frags) = (ms) * (rev/sec) * (sect/rev) /
* ((sect/frag) * (ms/sec))
* then round up to the next block.
*/
nextblk += roundup(fs->fs_rotdelay * fs->fs_rps * fs->fs_nsect /
(NSPF(fs) * 1000), fs->fs_frag);
/*
* Here we convert ms of delay to frags as:
* (frags) = (ms) * (rev/sec) * (sect/rev) /
* ((sect/frag) * (ms/sec))
* then round up to the next block.
*/
nextblk += roundup(fs->fs_rotdelay * fs->fs_rps * fs->fs_nsect /
(NSPF(fs) * 1000), fs->fs_frag);
return (nextblk);
}