On 1/21/07, Ralf Baechle <ralf@xxxxxxxxxxxxxx> wrote:
The overhead of timer interrupts at this low clockrate is significant so I recommend to minimize the timer interrupt rate as far as possible. This is really a tradeoff between latency and overhead and matters much less on hardcores which run at hundreds of MHz. For power sensitive applications lowering the interrupt rate can also help. And that's alredy pretty much what you need to know, that is a 10ms timer is fine.
I have worked with FPGA Linux system which is reconfigurable on-the-fly by the 200Mhz ARM9 CPU running Debian Linux, Altera Cyclone II FPGA is included on my TS-7300 board. Advantage is, Altera FPGA and a dedicated high-speed bus between the CPU and FPGA provides a good design scope to provide many solutions. Coming to boot up (by an USB 1GB SD card), by doing enough software tuning bootup to a Linux prompt takes just 1.69 seconds after power-up. If I remember correctly, SD image will look at the state of jumper 6 (should be put ON), the full Debian bootup will be bypassed and the system will instead drop straight to a shell prompt. 1.69 seconds after power-on the serial console prompt is active and 2.41 seconds after power-on the video console is displayed. This software is based on Debian & has a vendor supplied Linux boot loader. Currently am working (slowly in free time) to bring the whole thing to FC6. Shall post the progres...
Ralf
~Akula2
