Baumgart, Donald (donald.baumgart++at++cdott.com)
Tue, 14 Sep 1999 11:35:00 -0400
Did the upgrade to IRIX 6.5.5 solve your problems??? Did it cause any
problems with Vega?? We have a similar problem that may be related to this
frame rate bug. We have used the 'npri' command to improve our situation.
We are wondering if the upgrade is worth it right now, or will we run into
more problems?
Thanks for any info.
Don Baumgart
----------------------------------------------------
Don Baumgart
System/Software Engineer
Computing Devices Canada
A General Dynamics Company
613-596-7454
----------------------------------------------------
-----Original Message-----
From: allan++at++southpark.engr.sgi.com [mailto:allan++at++southpark.engr.sgi.com]
Sent: Wednesday, August 25, 1999 12:51 PM
To: Wear, Mark; 'Info-Vega'
Cc: 'Info-Performer'
Subject: Re: Frame Rate
On Aug 25, 7:25am, Wear, Mark wrote:
> PROBLEM:
> When I limit the frame rate to 30Hz, the simulation runs 30 Hz with
frequent
> drops to 20 Hz. However, when I limit the frame rate to 60 Hz, the
> simulation runs 30 Hz with occasional jumps to 60 Hz (during roll). If the
> simulation can run 30 Hz when asking for 60 Hz, why can it not run 30 Hz
> when limiting to 30 Hz? What is going on here?
I assume you're running IRIX 6.5.x. This is an IRIX bug that was
introduced in IRIX 6.5 and just recently fixed for IRIX 6.5.5. The
best overall solution would be to upgrade unless this causes problems
for Vega. IRIX 6.5.5 is on the SGI website (support.sgi.com) and
CD's should be shipping around now.
Here's what's mentioned in the Performer relnotes;
6.1.1 Problems_fixed_in_IRIS_Performer_2.2.6
o A change in the semantics of sginap() could cause
frames to be missed if the application was running in
FLOAT or LOCK phase and finishing its frame more than a
full video field early. See Chapter 4 of these release
notes for more details. This has been fixed in IRIX
6.5.5 (SCR 635983).
[and from Chapter 4:]
4.1 IRIX 6.5
In IRIX 6.5 through IRIX 6.5.4, a change in the semantics of
sginap() can cause frames to be missed if the application is
running in FLOAT or LOCK phase and finishing more than a
full field early. The sginap() call is used by IRIS
Performer specifically in the case where the application
finishes more than a full field ahead of schedule. This
does not affect applications running at field rate (ie. 60
Hz) or applications running at their requested rate.
A workaround is to give the program a realtime scheduling
priority using the npri program (which must be run as root
or with the CAP_SCHED_MGT capability):
# npri -s RR -r <any number 0-255> <program> <args>
or:
# npri -s FIFO -r <any number 0-255> <program> <args>
To allow users to run npri without full root permissions,
you can give the npri program the set-capability-on-
execution attribute:
# chcap CAP_SCHED_MGT+eip /usr/sbin/npri
If you later want to change it back:
# chcap all= /usr/sbin/npri
See the npri(1) and chcap(1) references pages for more
information.
-- Allan Schaffer allan++at++sgi.com Silicon Graphics http://reality.sgi.com/allan
This archive was generated by hypermail 2.0b2 on Tue Sep 14 1999 - 08:35:25 PDT