Kernel 2.6.22.14. Create a tree of directories containing tens or hundreds of thousands of symlinks and run
find linkfarm | program-that-readlinks-the-file-names-in-its-stdin Memory usage will grow and grow until the system starts to swap, after which you are SOL. The combined effects of thrashing and the OOM killer will render your system catatonic for a long time and if it finally recovers, you probably won't be able to log in. With 1 GB of RAM, the tipping point is somewhere above 700,000 symlinks. So you kill the pipe before it starts to swap. Memory usage does not go down. Try "sync" or "umount /linkfarm". They will block for minutes, during which memory usage goes down slowly, on the order of 1 MB per second. All the while, iostat indicates several hundred transactions per second on the disk where the link farm resides. All this crap appears to be related to the updating of the atimes after a readlink. I understand that the problem could be alleviated by mounting the file system noatime or relatime, but this not just a performance problem. You should not be able to make your system unusable with just one process making readlink() calls. As a stop gap, is there an equivalent of O_NOATIME for readlink() ? -- André Majorel <URL:http://www.teaser.fr/~amajorel/> Do not use this account for regular correspondence. See the URL above for contact information. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
