Re: PCI speed??
On di, 2002-10-15 at 03:52, Richard Fillion wrote:
> I recently ran an hdparm -t test on my ide disk (new ATA100 one) against
> my original scsi disk, and it lost, by quite a bit too. After some
> toying around i realized that the ide-disk module was using 33Mhz for
> transfers. It's an Ultra100 controller, so it better damn well do more
> than 33Mhz. So i tried unloading the module and reloading it with
> "idebus=66", but i get errors saying its not a valid option.
Ultra100 means that the highest rate it has is 100 Mbyte/second over the
ide cable, which has nothing to do with the clockfrequency on the PCI
bus in MHz. 33 MHz is more than fast enough for IDE disks, because the
theoretial maximal rate the PCI bus has is 132 Mbyte/sec. This idebus
parameter is needed for systems with a VESA local bus (as found on many
i486 systems), where the busspeed can be 33, 40 or 50 MHz.
And if you really read that message carefully, it says it uses this
value only for PIO modes, while for performance you'll want to use DMA
modes instead of PIO modes.
> So, i was wondering, do alphas only have 33mhz pci buses or something?
> is there a reason i cant get over that speed going? 7megs/sec transfer
> isnt exactly lightning fast. Especially seeing how i use it for swap
> now too.
All Alpha's I have use either SCSI or NFS, but I believe that many
Alpha's are not known for their fast IDE performance. If you tell us
what type of Alpha you have, maybe someone else on this list can tell
you what to do.
--
Tot ziens,
Bart-Jan Vrielink
Reply to: