Erich Titl wrote: >Eric > >[EMAIL PROTECTED] wrote: > > >>I don't follow you here. Why do you wan't to use loop mounted cramfs? Does >>it use RAM or ROM (Flash/HD/Floppy/..). The advantage of full RAM based >>systems is that you can unmount the storage media. Besides the footprint >>of Bering-uClibc with base packages is only ~8Mb. >> >> > >Yes, but look at it when it holds ipsec, ssh, samba, squid... > >A loop mounted cramfs looks (for read_only operations) exactly like a >part of the file system tree. The benefit of this is that, even on ram, >it cannot be trivially modified and it takes a lot less RAM space >because it compresses its contents. > >
Are you really sure about that? I am not really familiar with how the tmpfs or ramfs works, but to me sounds logical that when you execute something on a tmpfs dist, the memory is never copied from ramdisk to RAM, because it is already in ram. It should be possible to run it from 1 single copy in RAM. But if you run it from a mounted loopdevice in ram, the code needs to be uncompressed and then executed. That means you will need a copy of the compressed code and one copy of the uncompressed. So if the compression ratio is 50% a compressed cramfs image on a tmpfs would take 50% more ram to execute the same code than if you just runs it "natively" from tmpfs. Again, I don't know how cramfs or tmpfs works so I could be completely wrong about this but I think is sounds logical. Also, the nature of Bering uClibc is that you only need to unpack the needed packages to RAM, so you are probably using the packages that are extracted to RAM. On a normal disk based system, the linux kernel would cache the used executable data from disk to RAM so the memory will be used anyway - but the kernel has the option to free it if needed for other things. When running from RAM you will only prevent the kernel from releasing the memory to use on other things wich guarantees you an ultrafast system. Adding a swap disk is also an interesting topic... You will save RAM when mounting a cramfs image on cdrom or mount a disk, but the difference is maybe not so big as you might think. -- Natanael Copa ------------------------------------------------------- SF.Net email is Sponsored by the Better Software Conference & EXPO September 19-22, 2005 * San Francisco, CA * Development Lifecycle Practices Agile & Plan-Driven Development * Managing Projects & Teams * Testing & QA Security * Process Improvement & Measurement * http://www.sqe.com/bsce5sf _______________________________________________ leaf-devel mailing list leaf-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/leaf-devel
