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Improve the delay algorithm used in bgfsck. From the author:

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shuffles the timing and sleep calls in bgfsck from:

 sleep timer_on io timer_off io io io io io io io
   to
 sleep io io io io io io io timer_on io timer_off

 The original method basically guaranteed that the timed I/O included a
 disk seek every time, which made bgfsck sleep for much longer than
 necessary.

Submitted by:   Dan Nelson
Reviewed by:    kirk
This commit is contained in:
Scott Long 2004-05-18 19:51:41 +00:00
parent 4c0d8029dc
commit 08983aee40
1 changed files with 6 additions and 4 deletions
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10
sbin/fsck_ffs/fsutil.c
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@ -478,10 +478,9 @@ void
slowio_start()
{
/* Delay one in every 8 operations by 16 times the average IO delay */
/* Delay one in every 8 operations */
slowio_pollcnt = (slowio_pollcnt + 1) & 7;
if (slowio_pollcnt == 0) {
usleep(slowio_delay_usec * 16);
gettimeofday(&slowio_starttime, NULL);
}
}
@ -501,9 +500,12 @@ slowio_end()
(tv.tv_usec - slowio_starttime.tv_usec);
if (delay_usec < 64)
delay_usec = 64;
if (delay_usec > 1000000)
delay_usec = 1000000;
if (delay_usec > 2500000)
delay_usec = 2500000;
slowio_delay_usec = (slowio_delay_usec * 63 + delay_usec) >> 6;
/* delay by 8 times the average IO delay */
if (slowio_delay_usec > 64)
usleep(slowio_delay_usec * 8);
}
/*