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lostevil

Member

Registered: 2009-11-06

Posts: 13

DMA not working with my SATA HDD (Nforce4 chipset)

My motherboard is an Asus A8N-SLI with nforce4 chipset, and the problem is that everytime the HDD is working my CPU gets a very low performance because (it seems) DMA is not working.
I've seen this:
http://http.download.nvidia.com/XFree86 … blems.html
But it's strange, because it says this only happens in old distributions, so I'm not sure if this could be related.

hdparm -Tt /dev/sda

/dev/sda:
 Timing cached reads:   1220 MB in  2.00 seconds = 609.67 MB/sec
 Timing buffered disk reads:  152 MB in  3.01 seconds =  50.57 MB/sec

lspci | grep -i ide

00:06.0 IDE interface: nVidia Corporation CK804 IDE (rev f2)
00:07.0 IDE interface: nVidia Corporation CK804 Serial ATA Controller (rev f3)
00:08.0 IDE interface: nVidia Corporation CK804 Serial ATA Controller (rev f3)

"lspci | grep -i sata" outputs nothing.

hdparm /dev/sda

/dev/sda:
 multcount     =  1 (on)
 IO_support    =  0 (default)
 readonly      =  0 (off)
 readahead     = 256 (on)
 geometry      = 30401/255/63, sectors = 488397168, start = 0

lsmod|grep ata

pata_amd               15652  0
pata_acpi               5824  0
ata_generic             6244  0
sata_nv                29292  5
libata                193612  4 pata_amd,pata_acpi,ata_generic,sata_nv
scsi_mod              133592  5 usb_storage,sg,sr_mod,sd_mod,libata

Is anybody facing the same problem?

Last edited by lostevil (2009-11-16 18:32:38)

fphillips

Member

From: Austin, TX

Registered: 2009-01-24

Posts: 202

Re: DMA not working with my SATA HDD (Nforce4 chipset)

50MB/s seems like DMA is working... if it wasn't you'd probably be getting 5MB/s.

hdparm -i /dev/sda

dmesg|grep -i dma

You can try sudo hdparm -D1 -Xudma5 for example, but some drives can't be set to the highest mode they show with the -i option.

lostevil

Member

Registered: 2009-11-06

Posts: 13

Re: DMA not working with my SATA HDD (Nforce4 chipset)

50MB/s seems like DMA is working... if it wasn't you'd probably be getting 5MB/s.

You are right about the hdparm -Tt, it seems to be a normal output, but every time the hard drive is accessed, my CPU usage peeks and stays at 100% until the HDD operation ends, and it takes too much to end.

hdparm -i /dev/sda

dmesg|grep -i dma

You can try sudo hdparm -D1 -Xudma5 for example, but some drives can't be set to the highest mode they show with the -i option.

I will be away from that computer for a few days, so I'll be more concrete and post the outputs when I return.

lostevil

Member

Registered: 2009-11-06

Posts: 13

Re: DMA not working with my SATA HDD (Nforce4 chipset)

Earlier than I thought:

hdparm -i /dev/sda

/dev/sda:

 Model=WDC WD2500JD-00HBB0, FwRev=08.02D08, SerialNo=WD-WCAL72647665
 Config={ HardSect NotMFM HdSw>15uSec SpinMotCtl Fixed DTR>5Mbs FmtGapReq }
 RawCHS=16383/16/63, TrkSize=57600, SectSize=600, ECCbytes=74
 BuffType=DualPortCache, BuffSize=8192kB, MaxMultSect=16, MultSect=1
 CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=488397168
 IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120}
 PIO modes:  pio0 pio1 pio2 pio3 pio4
 DMA modes:  mdma0 mdma1 mdma2
 UDMA modes: udma0 udma1 udma2 udma3 udma4 udma5 *udma6
 AdvancedPM=no WriteCache=enabled
 Drive conforms to: Unspecified:  ATA/ATAPI-1,2,3,4,5,6

 * signifies the current active mode

hdparm -D1 -Xudma5 /dev/sda

/dev/sda:
 setting drive defect management to 1
 HDIO_DRIVE_CMD(defectmgmt) failed: Input/output error
 setting xfermode to 69 (UltraDMA mode5)
 HDIO_DRIVE_CMD(setxfermode) failed: Invalid exchange

So dma is working... but I'm still experiencing the CPU problem.

Mountainjew

Member

From: Ireland

Registered: 2008-08-24

Posts: 405

Re: DMA not working with my SATA HDD (Nforce4 chipset)

Isn't DMA irrelevant on Sata drives?

Btw, i'm also having this problem. Have been for months. It seems to be a kernel issue though, from what i've been reading anyway. Many people have resolved it by running BFS/BFQ schedulers. Neither of which have worked for me.

Here's some discussion about it at Gentoo forums http://forums.gentoo.org/viewtopic-t-482731.html

Oh more here http://bbs.archlinux.org/viewtopic.php?id=70525 and here http://bbs.archlinux.org/viewtopic.php?id=79319

Last edited by Mountainjew (2009-11-18 21:47:52)

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Last.fm

lostevil

Member

Registered: 2009-11-06

Posts: 13

Re: DMA not working with my SATA HDD (Nforce4 chipset)

So if it really is an I/O scheduler problem, none of the existants solve the problem to me.

http://www.redhat.com/magazine/008jun05 … chedulers/

I tried all of them and had the same problem.
@Mountainjew: Is your chipset a nforce4 one?

fphillips

Member

From: Austin, TX

Registered: 2009-01-24

Posts: 202

Re: DMA not working with my SATA HDD (Nforce4 chipset)

As I recall, BFS is a cpu scheduler, which are not pluggable like the I/O schedulers, hence te needed kernel patch.

The kernel devs don't want to make the cpu scheduler modular, rather they want to keep a single solution for all machines. This is part of the reason Con left.

P.S. There has historically been trouble with the nforce drivers, maybe you have experienced some of these before.

Last edited by fphillips (2009-11-19 18:04:09)