Per "PCI System Architecture" 4th edition (a great resouce), the top speed of the 32bit 33Mhz PCI bus is 132Mbytes/sec in burst mode. However, there are many things that can slow it down. There are many systems that use the bus, and the bus arbitator decides how much each device gets to use the system. It is possible for something to "hog" some of the system. It is also possible that the transfer is being done in non-burst mode, and the transfer may be 32, 24, 16 or 8 bits. In the slowest case, the pci bus can spend several cycles setting up the transfer, transfer one byte, then do it again.
If you have more questions check out the book that I cited above. -----Original Message----- From: Pablo Alvarez [mailto:[EMAIL PROTECTED]] Sent: Friday, February 22, 2002 8:32 AM To: [EMAIL PROTECTED] Subject: [rtl] PCI bus transfers Hi all, This is not strictly an RTLinux question, but I hope you can help: we are transferring data across the PCI bus, and it seems to be quite slow. The manufacturer (Dell) claims that the PCI bus speed is 33 MHz. Am I missing something in translating that 33 Mbits/sec? Or should I believe that, since it is a 32-bit bus, it's actually 32*33 = 1056 Mbits/sec? Or are only some of the 32-bits actually used to transmit data? Thanks, Pablo Alvarez -- [rtl] --- To unsubscribe: echo "unsubscribe rtl" | mail [EMAIL PROTECTED] OR echo "unsubscribe rtl <Your_email>" | mail [EMAIL PROTECTED] -- For more information on Real-Time Linux see: http://www.rtlinux.org/ -- [rtl] --- To unsubscribe: echo "unsubscribe rtl" | mail [EMAIL PROTECTED] OR echo "unsubscribe rtl <Your_email>" | mail [EMAIL PROTECTED] -- For more information on Real-Time Linux see: http://www.rtlinux.org/
