Messages in this thread | | | Date | Mon, 19 Mar 2001 14:33:41 -0500 | From | Jeremy Jackson <> | Subject | Re: UDMA 100 / PIIX4 question |
| |
Tim Moore wrote:
> quintaq@yahoo.co.uk wrote: > > I have an IBM DTLA 307030 (ATA 100 / UDMA 5) on an 815e board (Asus CUSL2), which has a PIIX4 controller. > > ... > > My problem is that (according to hdparm -t), I never get a better transfer rate than approximately 15.8 Mb/sec. I achieve this when DMA is enabled, - without it I fall back to about 5 Mb /sec. No amount of fiddling with other hdparm settings makes any difference. > > ... > > 15MB/s for hdparm is about right.
Yes, since hdparm -t measures *SUSTAINED* transfers... the actual "head rate" of data reads from disk surface. Only if you read *only* data that is alread in harddrive's cache will you get a speed close to the UDMA mode of the drive/controller. The cache is around 1Mbyte, so for a split-second re-read of some data....
> > > "...four IDE devices can be supported in Bus Master mode. > PIIX4 contains support for "Ultra DMA/33" synchronous DMA > compatible devices." > > http://developer.intel.com/design/intarch/techinfo/440BX/PIIX4_intro.htm > > -- > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |