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#1 2007-10-06 10:23:22
- venomous
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- Registered: 2007-03-18
- Posts: 7
Poor HDD performance - possibly no dma
Hello. I've very sluggish system performance when trying to copy large amounts of data from one HDD to another. It's like every few seconds the system completely freezes for a second or so. Very annoying. If feels like DMA may be disabled, but when I tried hddparm, with which this problem used to be solved, hddparm -d device outputs nothing about DMA, and hddparm -d 1 device fails with "inappropriate ioctl for device" - for all 3 drives connected.
I've nforce4-based asrock alivenf6g-vsta motherboard, and archlinux installed from "don't panic" CD, with minimal updates. I'm trying to copy from an IDE hard disk to SATA2 hard disk.
Anyone knows what can be done about this? Thanks.
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#2 2007-10-07 02:29:41
- byte
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- From: Düsseldorf (DE)
- Registered: 2006-05-01
- Posts: 2,046
Re: Poor HDD performance - possibly no dma
Output of 'dmesg | grep -i ata.*dma' and 'hdparm --direct -tT /dev/sda' (and sdb or whatever fits your setup), please.
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#3 2007-10-07 13:20:06
- venomous
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- Registered: 2007-03-18
- Posts: 7
Re: Poor HDD performance - possibly no dma
I tried that dmesg command and it looks like DMA is getting enabled. Anyway, I did some experimentation and I think I figured out what the problem was - kjournald was eating a lot of CPU. Maybe because that HDD is pretty big or for some other reason. Anyway, now that I stripped off the journal making it ext2 instead of ext3 I no longer get any noticeable lags. So it must have been the journal. Sorry for annoyance...
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#4 2007-10-07 14:38:33
- byte
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- From: Düsseldorf (DE)
- Registered: 2006-05-01
- Posts: 2,046
Re: Poor HDD performance - possibly no dma
Just a bit more info here...
If you look at dmesg you'll see a line like "kjournald starting. Commit interval 5 seconds". So, when doing a lot of heavy disk-I/O, everything grinds to a halt every 5 seconds because the journal needs to be brought in sync. So if you mount the ext3 partition(s) with, say, commit=20 it should run smoother.
Last edited by byte (2007-10-07 14:39:58)
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