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January 5th, 2004 06:00
Inspiron 5150 - SpeedStep - QueryPerformanceCounter
Hardware: Inspiron 5150 3.2GHz Mobile Pentium 4 with HT. Software: BIOS A29, XP SP1 + updated Mobile Pentium driver (1264)
Our programs use the standard windows system calls QueryPerformanceCounter to measure time durations.
Since I got unexpected results from that, I made a small test program.
What it does is: It runs in a loop, sleeping 1000 ticks and then printing the difference between the startup time and the current time measured using four different methods: The system tickcount, a MultiMedia timer, QueryPerformanceCounter and using the RDTSC CPU instruction.
When I run using the power settings: Dekstop/Always On, I get:
PerformanceFrequency: 3189400000
Tick 1.000, MM: 1.000, Performance: 1.000, RDTSC: 1.000
Tick 2.000, MM: 2.000, Performance: 2.000, RDTSC: 2.000
Tick 3.000, MM: 3.000, Performance: 3.000, RDTSC: 3.000
However, when I run at the normal settings Portable/Laptop I get:
PerformanceFrequency: 3189400000
Tick 1.000, MM: 1.000, Performance: 0.500, RDTSC: 0.500
Tick 2.000, MM: 2.000, Performance: 1.000, RDTSC: 1.000
Tick 3.000, MM: 3.000, Performance: 1.500, RDTSC: 1.500
As one can see, the QueryPerformanceCounter derived time updates at about half the speed.
They update at the same speed as the CPU time counter, making me believe that the Microsoft driver doesn't compensate for changing the frequency due to power savings. Note that the number returned by RDTSC and QPF are different indicating that MS does something different than RDTSC.
Note that MS reports the correct frequency 3189MHz and 1594MHz.
I have tried the same on a Compaq Evo (Mobile Pentium 4 running at 1.7 and 1.1GHz respectively). There all answers are in sync. Note that the compaq used a 'processr.sys' and the Inspiron uses 'intelppm.sys' as the driver for the Processor.
Any ideas?
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bluetracker
2 Intern
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369 Posts
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January 5th, 2004 06:00
Just one really........the speedstep drivers are provided by the laptop manufacturer(http://support.intel.com/support/processors/mobile/pentiumiii/sb/CS-007509.htm). On your evidence it's clear that the DELL speedstep driver(intelppm.sys) is not doing it's job.
Instructor_Phil
10 Posts
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January 5th, 2004 19:00
Hi Mug,
Instructor_Phil here, I've got a brand new INSPIRON 5100 2.66 GHz with a ATI 7500 64MB graphic card and 512 Mb mem.
I am having problems while running on battery and this could be linked to SPEED STEP as well.
Could you, or any one else reading this with a 5100 or 5150, try playing a Mpeg2 or VOB file off their hard drive (Not DVD or CD-R) while running on battery power.
Please make sure the Mpeg2 file is of a high bit rate (6-15 Mbits/s) this will show you get smoove or stuttering playback.
Also, please switch back and forth between windowed and full screen mode during playback.
DOES YOURS WORK OK ??????
Phil.
mug
2 Posts
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January 6th, 2004 03:00
Hello Instructor_Phil,
My graphicscard is a NVIDIA GeForceFX Go5200, so that results are not necessarely comparable.
I did play VDO files from a USB Harddisk whilst on battery power with no jitter problems whatsoever.
Mug.
NoahB
54 Posts
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January 6th, 2004 12:00
I think your Smigwunker is set on German, while your wallygobble is set on Geekspeak.
Try setting everything on English and everything should work fine. Hope this helps, it made me feel much better. Have a great day.
Instructor_Phil
10 Posts
0
January 12th, 2004 21:00