Re: [gentoo-user] Slow HD

[Mark Knecht <markknecht@gmail.com>]

On 8/17/05, Pupeno <pupeno@pupeno.com> wrote:
> On Wednesday 17 August 2005 18:44, Mark Knecht wrote:
> > A quick test would be
> >
> > hdparm -tT /dev/hda
> I got this:
> /dev/hda:
>  Timing cached reads:   1344 MB in  2.00 seconds = 672.10 MB/sec
>  Timing buffered disk reads:    8 MB in  3.51 seconds =   2.28 MB/sec
> 
> > (or whatever drive you are concerned about.) Greater than 15MB/S is
> > almost certainly DMA but good DMA from newer drives should be
> > 25-50MB/S
> The second speed is evidently wrong.

Not wrong, just not DMA. BTW - as has been pointed out here before -
do not take these numbers as a serious test of real disk speeds. This
is a just a quick way of looking.

> 
> > You can look at the drives parameters using hdparm and reading through
> > the man page to understand what all the values mean.
> I tried to enable dma, but this happened:
> # hdparm -d1 /dev/hda
> 
> /dev/hda:
>  setting using_dma to 1 (on)
>  HDIO_SET_DMA failed: Operation not permitted
>  using_dma    =  0 (off)
> 
> What am I doing wrong ? some kernel option ?

Possibly. Many of the ATAPI DMA drivers are supplied when you enable
the proper chipset support in make menuconfig under Device Drivers ->
ATA support.

What chipset is your machine using? (lspci)

>From my laptop:

flash linux #  hdparm /dev/hda

/dev/hda:
 multcount    = 16 (on)
 IO_support   =  0 (default 16-bit)
 unmaskirq    =  0 (off)
 using_dma    =  1 (on)
 keepsettings =  0 (off)
 readonly     =  0 (off)
 readahead    = 256 (on)
 geometry     = 65535/16/63, sectors = 80026361856, start = 0
flash linux #

flash linux #  hdparm -tT /dev/hda

/dev/hda:
 Timing cached reads:   1788 MB in  2.00 seconds = 891.91 MB/sec
 Timing buffered disk reads:   82 MB in  3.04 seconds =  26.93 MB/sec
flash linux #

Cheers,
Mark

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