Many older PC memory controllers don't cache more than 64MB of system RAM. In the case that you want more than 64MB of RAM, the net result will usually be a slowdown in overall performance due to the kernel running out of uncached memory (it is loaded at the top of memory).

The solution is the slram MTD driver. Pass mem=64M to the kernel to force it to load within the cached region, and then use slram to allocate the rest of system memory. This gives you a block device which you can use as a scratchpad, tmpfs, or even better, a swap area! Swapping to RAM (even uncached RAM) is much faster than swapping to disk in any case. I did this on my Toshiba Tecra 500CDT. The system has 144MB RAM but only 64MB is cacheable. It runs like a champ, and I don't need a swap partition on disk this way.

The first time I described this idea to someone, he thought I was crazy. I realized why the reaction was such. Just think if you told someone that the magic secret to speeding up your system is to "put your swapfile on a RAM disk"...

Score:3, Interesting