On Wednesday 17 August 2005 22:15, Mark Knecht wrote: > On 8/17/05, Pupeno <[EMAIL PROTECTED]> 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. Should I leave DMA off ? Isn't almost always faster to use DMA ?
> > > 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. I have all of them enabled as modules. > What chipset is your machine using? (lspci) 0000:00:1f.1 IDE interface: Intel Corporation 82801DBM (ICH4-M) IDE Controller (rev 01) > 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) Here, your dma is 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 # Thanks. -- Pupeno <[EMAIL PROTECTED]> (http://pupeno.com) Reading ? Science Fiction ? http://sfreaders.com.ar
pgp9pSTJYGCI0.pgp
Description: PGP signature
