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. 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 -- gentoo-user@gentoo.org mailing list
