Hello All,
I am working on/with RTAI/RT-Linux for a while now in combination
with XFree 4.0.1 and have some problems that are maybe X related.
For the ones that don't know RTAI/RT-Linux it is an layer between the
hardware and the Linux kernel. The linux kernel never disables
interrupts
with the cli/sti instructions but uses a software implemented version.
That
way the layer between the linux kernel and the hardware kan preempt the
total
linux kernel for hardrealtime tasks and ISR's. The latency for those
hardrealtime
tasks is in the range 5-30usec which is about the best PC hardware can
give (for
more info on this see www.rtai.org and www.rtlinux.org)
Now the problem i and a few other developers have seen is that with
XFree 4.0.x
the latency gets unpredicatable. On of the causes is the use of cli/sti
intructions
in the X server. But after removing those the problem didn't go away.
Wath i noticed was latency upto 50msec more than 10 times as much than
acceptable.
This went away by disableing acceleration on my s3virge DX clone card.
Someone
else had simmulair problems with NVidia drivers.
After talking to some other developers the looking for an answer goes in
the direction
of a PCI bus lockup of somekind (but 50msec long delay, the 100-200usec
that the person
with the NVidia AGP card saw could be explained by that). And why only
when using acceleration ?
So my question, does anybody know what in the s3virge driver could cause
a latency of
10-50msec for hardware interupts to be handled (hardware info see below)
? And why does
this not happen when acceleration is turned off ?
TIA,
Erwin
My system:
ASUS AV7 (VIA KT133 chipset)
Athlon TB 800MHz
Infinion PC133 128MB DIMM
Haupauge WinTV card (module not loaded)
Dawicontrol (DC 2975U) SCSI controler (only for CD-rom and scanner)
HD IBM-DJNA-371350
NIC VIA chipset (dunno the cardbrand)
G-card: S3 Inc. ViRGE/DX or /GX (rev 1).
(see proc/pci below)
Software:
Kernel 2.2.16
RTAI 1.5
XFree 4.0.1
updated RH 6.2 install
compiler egcs-2.91.66
glibc 2.1.3
modutils 2.3.17
/proc/pci
PCI devices found:
Bus 0, device 0, function 0:
Host bridge: VIA Technologies Unknown device (rev 2).
Vendor id=1106. Device id=305.
Medium devsel. Master Capable. No bursts.
Prefetchable 32 bit memory at 0xe0000000 [0xe0000008].
Bus 0, device 1, function 0:
PCI bridge: VIA Technologies Unknown device (rev 0).
Vendor id=1106. Device id=8305.
Medium devsel. Master Capable. No bursts.
Bus 0, device 4, function 0:
ISA bridge: VIA Technologies Unknown device (rev 34).
Vendor id=1106. Device id=686.
Medium devsel. Master Capable. No bursts.
Bus 0, device 4, function 1:
IDE interface: VIA Technologies VT 82C586 Apollo IDE (rev 16).
Medium devsel. Fast back-to-back capable. Master Capable.
Latency=32.
I/O at 0xd800 [0xd801].
Bus 0, device 4, function 2:
USB Controller: VIA Technologies VT 82C586 Apollo USB (rev 16).
Medium devsel. IRQ 15. Master Capable. Latency=32.
I/O at 0xd400 [0xd401].
Bus 0, device 4, function 3:
USB Controller: VIA Technologies VT 82C586 Apollo USB (rev 16).
Medium devsel. IRQ 15. Master Capable. Latency=32.
I/O at 0xd000 [0xd001].
Bus 0, device 4, function 4:
Host bridge: VIA Technologies Unknown device (rev 48).
Vendor id=1106. Device id=3057.
Medium devsel. Fast back-to-back capable.
Bus 0, device 9, function 0:
Ethernet controller: VIA Technologies Unknown device (rev 6).
Vendor id=1106. Device id=3043.
Medium devsel. IRQ 15. Master Capable. Latency=64. Min
Gnt=118.Max Lat=152.
I/O at 0xa400 [0xa401].
Non-prefetchable 32 bit memory at 0xdd800000 [0xdd800000].
Bus 0, device 11, function 0:
Multimedia video controller: Brooktree Bt878 2nd Contr. (?) (rev 2).
Medium devsel. Fast back-to-back capable. IRQ 10. Master
Capable. Latency=32. Min Gnt=16.Max Lat=40.
Prefetchable 32 bit memory at 0xdf000000 [0xdf000008].
Bus 0, device 11, function 1:
Multimedia controller: Brooktree Bt878 (rev 2).
Medium devsel. Fast back-to-back capable. IRQ 10. Master
Capable. Latency=32. Min Gnt=4.Max Lat=255.
Prefetchable 32 bit memory at 0xde800000 [0xde800008].
Bus 0, device 12, function 0:
VGA compatible controller: S3 Inc. ViRGE/DX or /GX (rev 1).
Medium devsel. IRQ 5. Master Capable. Latency=32. Min
Gnt=4.Max Lat=255.
Non-prefetchable 32 bit memory at 0xd8000000 [0xd8000000].
Bus 0, device 13, function 0:
SCSI storage controller: NCR 53c875 (rev 38).
Medium devsel. IRQ 15. Master Capable. Latency=134. Min
Gnt=17.Max Lat=64.
I/O at 0xa000 [0xa001].
Non-prefetchable 32 bit memory at 0xd7800000 [0xd7800000].
Non-prefetchable 32 bit memory at 0xd7000000 [0xd7000000].
Bus 0, device 17, function 0:
Unknown mass storage controller: Promise Technology Unknown device
(rev 2).
Vendor id=105a. Device id=d30.
Medium devsel. IRQ 10. Master Capable. Latency=32.
I/O at 0x9800 [0x9801].
I/O at 0x9400 [0x9401].
I/O at 0x9000 [0x9001].
I/O at 0x8800 [0x8801].
I/O at 0x8400 [0x8401].
Non-prefetchable 32 bit memory at 0xd6800000 [0xd6800000].
/proc/cpuinfo
processor : 0
vendor_id : AuthenticAMD
cpu family : 6
model : 4
model name : AMD Athlon(tm) Processor
stepping : 2
cpu MHz : 807.213
cache size : 256 KB
fdiv_bug : no
hlt_bug : no
sep_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 1
wp : yes
flags : fpu vme de pse tsc msr 6 mce cx8 sep mtrr pge 14 cmov
fcmov 17 psn 22 mmx 24 30 3dnow
bogomips : 1612.19
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For more information on Real-Time Linux see:
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