Messages in this thread | | | From | Denis Vlasenko <> | Subject | Re: PROMBLEM: CD burning at 16x uses excessive CPU, although DMA is enabled | Date | Tue, 9 Apr 2002 11:33:40 -0200 |
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On 8 April 2002 13:47, Anssi Saari wrote: > I didn't really know how to put it. Maybe system load would be better. But > the actual problem is, I effectively can't burn audio and other types > at 16x in Linux, while there is no problem in some other operating systems > with the same hardware and applications. > > Here're some time figures from cdrdao: > > cdrdao simulate -n --speed 8 foo.cue 2.62s user 3.37s system 1% cpu > 6:41.86 total cdrdao simulate -n --speed 12 foo.cue 2.78s user 29.91s > system 12% cpu 4:31.71 total cdrdao simulate -n --speed 16 foo.cue 2.67s > user 128.77s system 52% cpu 4:10.68 total > > So yes, system time goes up quite steeply. > > But even though 50% is quite high, CPU load is not the problem as such, > the problem is getting data to the writer fast enough. And it's not > happening. Even a single audio track that is completely cached so that > there is no HD access has problems. It's like somehow accessing the CD > writer hogs the system for such long periods that there is insufficient > time to fill the writing program's buffer.
You may try profiling kernel to see where it exactly spending that time. It has an added benefit: you will learn how to profile kernels (if you don't know how to do it already).
I am waiting for similar problem to bite me to learn that, too. :-)
> One thing I noticed just now. If I turn off unmaskirq for the CD writer > with hdparm -u 0 /dev/hdc, it helps a little, but not enough. Time > reports now: > > cdrdao simulate -n --speed 16 foo.cue 2.75s user 75.18s system 58% cpu > 2:13.22 total -- vda - 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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