freebsd-nq/sys/i386
Bruce Evans b50641ef9c Fixed glitches (jumps) of about 1/HZ seconds for the i8254 timecounter.
The old version only worked right when the time was read strictly
more often than every 1/HZ seconds, but we only guarantee reading
it every (1/HZ + epsilon) seconds.  Part of rev.1.126-1.127 attempted
to fix this but didn't succeed.  Detect counter rollover using the
heuristic from the old version of microtime() with additional
complications for supporting calls from fast interrupt handlers.
This works provided i8254 interrupts are not delayed by more than
1/(2*HZ) seconds.

This needs more comments, and cleanups for the SMP case, and more
testing of the SMP case before it is merged into RELENG_3.

Tested by:		jhay
1999-05-28 14:08:59 +00:00
..
apm Divorce "dev_t" from the "major|minor" bitmap, which is now called 1999-05-11 19:55:07 +00:00
bios Divorce "dev_t" from the "major|minor" bitmap, which is now called 1999-05-11 19:55:07 +00:00
boot Back the last change out. 1999-05-25 10:30:52 +00:00
conf Add new Bt848/Bt878 driver options. 1999-05-28 10:27:22 +00:00
eisa Fix a [start,end] vs [start,count] botch that corrupted the resource 1999-05-24 03:08:46 +00:00
i386 Fixed glitches (jumps) of about 1/HZ seconds for the i8254 timecounter. 1999-05-28 14:08:59 +00:00
ibcs2 Fix a couple of warnings and some bitrot in comments. 1999-05-09 16:04:14 +00:00
include Fixed style bugs in previous commit. 1999-05-22 08:36:55 +00:00
isa Fixed glitches (jumps) of about 1/HZ seconds for the i8254 timecounter. 1999-05-28 14:08:59 +00:00
linux Divorce "dev_t" from the "major|minor" bitmap, which is now called 1999-05-11 19:55:07 +00:00
pci Move pcibus (host -> pci bus) probe/attach routines from nexus 1999-05-18 20:48:43 +00:00
svr4 Enable vmspace sharing on SMP. Major changes are, 1999-04-28 01:04:33 +00:00
Makefile Update to know about current kernel directory layout. 1999-02-28 22:14:16 +00:00