peter@hp-pcd.UUCP (Peter Robinson) (11/23/83)
#N:hp-pcd:19500007:000:1162
hp-pcd!peter Nov 18 10:55:00 1983
A couple of weeks ago I posted a query about our software clock losing
significant amounts of time (up to 5 minutes a day). My thanks to all those
who responded and in particular to Brian Thomson, who furnished the following
fix.
Since incorporating the change a week ago, we have lost only 17 seconds on
the clock.
Peter Robinson
Hewlett-Packard PCD
Corvallis, OR
{ucbvax!hplabs, harpo, ogcvax}!hp-pcd!peter
< VAX 750 running 4.1bsd >
---------------------------------------------------------------------------
< fix from Brian Thomson >
You are probably suffering from the infamous "bug fixed in 4.2",
discovered some years ago by a Mystery Person at Lucasfilm.
And it goes like this:
In clock.c, routine softclock(), the lines
if((p1 = calltodo.c_next) == 0 || p1->c_time > 0)
break;
should be replaced by
if((p1 = calltodo.c_next) == 0 || p1->c_time > 0) {
splx(s);
break;
}
The consequence of the bug is that the rest of softclock() used to
be executed at spl7(), which could make for missed clock interrupts.
Brian Thomson, CSRG Univ. of Toronto
{linus,ihnp4,uw-beaver,floyd,utzoo}!utcsrgv!thomson