Dear Marcelo, thanks for starting this discussion, and for providing a patch for 8xx.
However, I think we should not only look at the TLB handling problems on the 8xx processors. This is probably just a part of the problem. In general the 2.6 performance on (small) embedded systems is much, much worse than what we see with a 2.4 kernel. I put some results (2.4.25 vs. 2.6.11.7 on a MPC860 and on a MPC8240) at http://www.denx.de/twiki/bin/view/Know/Linux24vs26 Here is the summary: Using the 2.6 kernel on embedded systems implicates the following disadvantages: * Slow to build: 2.6 takes 30...40% longer to compile * Big memory footprint in flash: the 2.6 compressed kernel image is 30...40% bigger * Big memory footprint in RAM: the 2.6 kernel needs 30...40% more RAM; the available RAM size for applications is 700kB smaller * Slow to boot: 2.6 takes 5...15% longer to boot into multi-user mode * Slow to run: context switches up to 96% slower, local communication latencies up to 80% slower, file system latencies up to 76% slower, local communication bandwidth less than 50% in some cases. It's a disappointing result, indeed. Best regards, Wolfgang Denk -- Software Engineering: Embedded and Realtime Systems, Embedded Linux Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de Another megabytes the dust.
