On Wed, May 06, 2009 at 08:44:41AM +0200, Kolbj??rn Barmen wrote: > 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 :)
Also, what seemed to be different is that this compile called a shell script for each file being compiled. I'm not sure if that was generated by the Makefile at build time yet. My other thought is that GCC 4.1.x has a larger footprint than GCC 2.95 as it seemed to swap more than under the 2.4.30 / GCC 2.95.x. > > > 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? Point of clarification: I was changing the .config to remove support for hardware (don't even make as a module) and features that I don't need in the kernel. Was there another method being referred to with the term 'stripped' above? > > > 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" 500 > > > 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. Geert responded to this in a previous mail to the group, I have to get some information back to him. > > > 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 Thanks so much for this suggestion!!! I set the value to 200, and I so far have not seen the value (via vmstat) go below 200, lowest observed so far has been 244. This might be a good suggestion for m68k to make permanent? --Lance -- 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
