On Sun, 3 May 2009, Lance Tagliapietra wrote: > Observations: > a). I 2.4.30 kernel compile was about 6 hours on this hardware (GCC 2.95.4). > The 2.6.29 > took 4 days (GCC 4.1.2, Debian). That was without the modules, too. Now, it > did select > the config option for smallest code size, and perhaps that is not well > supported for m68k > and also added to the compile time. Make was done as nice -n 17 but the > system is mostly > idle, otherwise, but that is how I compile the 2.4.30.
Most of the times is spent "entering directory bla; : nothing to do here; leaving directory bla" - 2.6 is much bigger in terms of number of directories/files to parse through, and on slow IO that certainly matters :) > b). My custom 2.4.30 kernel size is about 750K uncompressed. With setting the > options to > remove support for hardware that I don't have and features that I don't need, > I still > came up with a kernel of 2.7M. The goal is to have the smallest footprint > kernel possible. My amiga kernel, which is not optimized for size, has ipv6 and lots of stuff,, is 2170192 bytes, stripped. I suspect you have not stripped yours? > c). The 2.6.26 kernel seems to want to keep more memory free and hit the swap > much more > than the 2.4.30 kernel according to vmstat. Under 2.4.30 I see the free > memory go as low > as about 200K, and it will remain at that level as long as is necessary. > Under 2.6.26, > the free memory stays at about 800K, and if it drops below that, it will come > back to that > level relatively quickly. What does "sysctl vm.min_free_kbytes" say? Here it says "vm.min_free_kbytes = 1763" > d). The real time clock came up on the worng month, going from 2.4.30 to > 2.6.26 (or 28), March vs April, in this case. Hm, this sounds familiar, allthough I cant pinpoint it. > e). Is there an option which tells the kernel the minimum amount of free RAM > to maintain > as I describe in (c) above? RAM is relatively precious in my m68k > environment, and having > 500k being held in reserve seems a bit much? I'd try with "sysctl -w vm.min_free_kbytes=500" and see if that helps. If it does, make it permanent by adding it to /etc/sysctl.conf > f). The kernel config gives options for 3 schedulers. Does anyone here know > which gives the > smallest memory footprint? I'm clueless on this one. -- kolla -- To unsubscribe from this list: send the line "unsubscribe linux-m68k" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
