overloaded PCI bus

[caseman]

What are the detrimental effects (if any) of a maxed out PCI bus? With two or three 15k 320 scsi drives in a RAID-0 one could hit that 133MB\Sec PCI bus ceiling. If I remember correctly the Maxtor drives were hitting around 70MB per second in a single drive set up. So, if you hit the max, what happens? Does your sound start to stutter or some other equally annoying thing or does every just happily keep running, with no additional performance?

 

[pIII_Man]

bus mastering is your freind!

PCI supports full device bus mastering, and provides bus arbitration facilities through the system chipset. PCI's design allows bus mastering of multiple devices on the bus simultaneously, with the arbitration circuitry working to ensure that no device on the bus (including the processor!) locks out any other device. At the same time though, it allows any given device to use the full bus throughput if no other device needs to transfer anything. In a way, the PCI bus acts like a tiny "local area network" inside the computer, in which multiple devices can each talk to each other, sharing a communication channel that is managed by the chipset.

<A HREF="http://www.pcguide.com/ref/mbsys/buses/types/pci.htm" target="_new">http://www.pcguide.com/ref/mbsys/buses/types/pci.htm</A>


If it isn't a P6 then it isn't a procesor
110% BX fanboy

 

[caseman]

reading that article brings back the good ol' days. When was that written by the way?

It's been my experience that running too many devices causes problems with all them (or in this case one device (scsi controller that hogs it all)). I've never actually tried to narrow it down or benchmark the performance issues, but my somewhat sketchy recollection tells me that there is a problem with a loaded PCI bus. Was this totally my imagination or is there something too that>?

 

[pIII_Man]

i could see how an overloaded pci bus could cause speed degration or possibly lockups, because after all bus mastering can only do so much when you are trying to pump 210mb/s through a 133mb/s bus. I would have to say that if you really want to get serious about scsi and things of that nature either get a 64 bit pci mobo or wait for pci ex.

BTW i would immagine that was writen in the 486 days when 32 bit buses were first being implimented (pci and vesa)

If it isn't a P6 then it isn't a procesor
110% BX fanboy<P ID="edit"><FONT SIZE=-1><EM>Edited by piii_Man on 11/02/03 06:50 PM.</EM></FONT></P>

 

[caseman]

Yeah, I know. I was hoping someone would convince me otherwise. Oh well.