Messages in this thread | | | From | Dieter Nützel <> | Subject | Re: Poor performance during disk writes | Date | Thu, 20 Dec 2001 14:27:17 +0100 |
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On Thursday, 20.12.201, 10:49 Helge Hafting wrote: > jlm wrote: [-] > > So I guess I don't really care what mode the hard drive is operating in > > (udma, mdma, dma or plain ide), I just don't want to have to go get a > > cup of coffee while the hard drive saves some data. Is there a "don't > > Devices generally get the cpu before anything else. A good disk system > don't need much cpu. Running IDE in PIO mode require a lot > of cpu though. Using any of the DMA modes avoids that.
Amen.. Sorry, Helge sure you are right in theory but try dbench 32 (maybe bonnie/bonnie++) and playing an MP3/Ogg-Vorbis in parallel... That's my first test on any "new" kernel version.
Even with an 1 GHz Athlon II, 640 MB, U160 DDYS 18 GB, 10k IBM disk (on an AHA-2940UW) it stutters like mad. I am running all my kernel _with_ Robert Love's preempt + lock-break patches and it doesn't solve the problem. CPU load is (very) low but it do not work like it should.
> > pre-empt the rest of the system" switch for the eide drives? Is there > > something fundamental/unique going on here that I'm missing? > dma, udma, etc. is that switch. It lets the cpu do other work (such as > redrawing X) while the disk is busy. Plain ide is what you don't want.
See above the whole system show some bad hiccup.
> The problem of waiting for other files or swapping while a really big > write is going on is different. Get more drives, so the big writes go > to one drive while you get stuff swapped in (or other file access) > on other drive(s). The kernel is capable of getting fast response > from one drive while another is completely bogged down with > enormous writes.
Tried this already. Neither I put my test files (MP3/Ogg-Vorbis) in /dev/shm or a nother disk it do not change anything.
There must be something in the VFS?
-Dieter
-- Dieter Nützel Graduate Student, Computer Science University of Hamburg @home: Dieter.Nuetzel@hamburg.de - 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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