>I find regular PCI bus (32bit) tops out at about 600 Mbits/sec on most >machines. For PCI-X (64 bit/133) a realistic value is 6 Gbits/sec. The >problem is arbitration and transfer sizes. >That means for for normal PCI32, one gigabit card or >6 100Mbit Ethernet interfaces can saturate the bus. Also, all that >I/O slows down the CPU and memory interface. I'm seeing issues with only 110Mbits/sec of traffic. Ultimately I expect to be using far more than that, but I really didn't expect to be overloading the bus yet. Leigh. -----Original Message----- From: Stephen Hemminger [mailto:shemminger@xxxxxxxxxxxxxxxxxxxx] Sent: Wednesday, 14 November 2007 9:47 AM To: Leigh Sharpe Cc: bridge@xxxxxxxxxxxxxxxxxxxxxxxxxx Subject: Re: Rx Buffer sizes on e1000 I find regular PCI bus (32bit) tops out at about 600 Mbits/sec on most machines. For PCI-X (64 bit/133) a realistic value is 6 Gbits/sec. The problem is arbitration and transfer sizes. Absolute limit is: PCI32 33MHz = 133MB/s PCI32 66MHz = 266MB/s PCI64 33MHz = 266MB/s PCI64 66MHz = 533MB/s PCI-X 133MHz = 1066MB/s That means for for normal PCI32, one gigabit card or 6 100Mbit Ethernet interfaces can saturate the bus. Also, all that I/O slows down the CPU and memory interface. -- Stephen Hemminger <shemminger@xxxxxxxxxxxxxxxxxxxx> _______________________________________________ Bridge mailing list Bridge@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/bridge
