Messages in this thread | | | From | Bill Davidsen <> | Subject | Re: tvtime and the Linux 2.6 scheduler | Date | Mon, 24 May 2004 15:38:45 -0400 |
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szonyi calin wrote: > --- Billy Biggs <vektor@dumbterm.net> a écrit : > I am the > author of tvtime, a TV application with advanced > >>image >>processing algorithms. Some users are complaining about poor >>performance under Linux 2.6, and I would like more information >>about how >>tvtime will be treated by the scheduler. Here is an example >>of the >>intended usage: >> >> - Program running as root and SCHED_FIFO >> - NTSC, input ~30 fps, each field processed for an output of ~60 fps ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^ >> - CPU intensive processing, say 9 ms per field on my P3-733 >> - with a typical AGP card, the X driver takes 4 ms to draw >> - Wait using /dev/rtc set to 1024 Hz >> >> for(;;) >> 9 ms : process frame >> 4 ms : draw frame >> 3 ms : wait until next field time using /dev/rtc >> 9 ms : process frame >> 4 ms : draw frame >> 3 ms : block on /dev/video0 for next frame >> ----- >> 33 ms : time per NTSC frame [___snip___] > For me it works ok > Running tvtime with 2.6.6-mm5 load average 26 (twenty six) it > works > almost perfect (no frame skipped -- at least not reported by > tvtime) > at full rate (50 frames/sec). Computer: AMD Duron 700 MHz, 256MB ~~~~~~~~~~~~~~~~^^^ > Ram, > VIA KT133 chipset, AGP 4x, Ati Radeon 7200
There have been pretty good explanations of this, so I'll just say that it might be that someone with a machine of limited capacity would be able to generate 50fps and not 60fps. In much of Europe the TV flickers at the same frequency as the lights ;-)
-- -bill davidsen (davidsen@tmr.com) "The secret to procrastination is to put things off until the last possible moment - but no longer" -me - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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