Ok, my outcome so far:1.) I have tuned my hd now (-d 1, -u 1, -m 16, -k 1), and that made a huge difference. Note the -k 1, this is important so the settings stay over sleep. It doesn't help just selecting DMA during kernel configuration, you seem to *have* to use hdparm to set at least -k 1 during boot/before your first sleep.
2.) I am now running 2.4.18 with http://penguinppc.org/~eb/files/2.4.18-elf-fix.patch and 2.4.18-rc1-low-latency.patch from Andrew Morton's Website (zipworld.com.au something) (and also the attached one). It runs, also mol is no problem; however: I've compiled it with the sysctl in /proc, and tried switching with
echo 1 > /proc/sys/kernel/lowlatency or echo 0 > ...but haven't noticed any difference whatsoever yet. I've mainly tried untarring kernel tarballs and copying around with or without nice and at the same time dragged a window around in X. The window is sluggish either way during phases where it seems the CPU is working and not the disk. Now I would have expected that since X runs with elevated priority (-10) it should profit from lower latency. I guess lowlat only helps for realtime priority processes? Maybe the O(1) schedular would help more in that case?
NOTE: the patch from Andrew Morton is x86 centric. To be able to enable lowlatency you need to apply the attached patch on top of 2.4.18-rc1-low-latency.patch
Note 2: in case you should ever be unable to boot your kernel since it stops in the middle of the process, but you can still scroll up and down in the console and it did (maybe 40 lines earlier) print 'Warning: unable to open initial console', then it's because you usually use devfs (and thus have no /dev directory tree on your disk) but forgot to enable devfs in that kernel .-)
Christian.
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-- Christian Jaeger Programmer & System Engineer +41 1 430 45 26 ETHLife CMS Project - www.ethlife.ethz.ch/newcms - www.ethlife.ethz.ch