From: Colin Blake [colin@theblakes.com]
Sent: Tuesday, October 23, 2001 11:17 AM
To: Info-VAX@Mvb.Saic.Com
Subject: Re: [MOZILLA] Burner of CPU time!!!

The UNIX code (from which the VMS version is built) expects to be able to select() on a set
of fd's that include the X connection number. On OpenVMS, the X connection number is NOT an
fd, and so this purely event driven model won't work for us without some major changes. So
we have to watch the fd's via a select, and also have to watch for X activity as well. The
way this is currently done (so as to not have to rewrite major chunks of Mozilla) is to
select() for a certain amount of time and then check for X activity. This polling mechanism
does, of course, cost in terms of CPU. And the more frequently you poll, the more
responsive the browser feels, but the more it costs you in terms of CPU. The current
settings were chosen to give good response without too much CPU usage. If you wish to
change the poll timers, you can. Look in MOZILLA.COM and you'll see VMS_POLL_TIMER_MIN,
VMS_POLL_TIMER_MAX, and VMS_POLL_TIMER_DELTA (they are currently commented out because the
default values are the same as the values in MOZILLA.COM). The poll timer is a sliding
timer; it starts at the MIN value and increases (each time there is no activity) by the
DELTA until it reaches MAX. It never goes past MAX and goes back to MIN each time there is
some activity. All values are in milli-seconds. A DELTA value of 0 indicates that the timer
should doubled each time there is no activity seen. Try playing. You may find some values
which work better for you.