Once upon a time, Dennis Kaptain <dennis.kaptain@xxxxxxxxx> said: > It still doesn't seem like an ideal way to handle /tmp when I have a > perfectly good partition and swapping is a major performance killer. > I'd rather disk access wait time is caused by accessing /tmp when I > need to rather than swapping tmpfs in and out for a program. Swapping tmpfs files to swap is no more of a performance killer than writing /tmp to disk to begin with (the same data would be written to the same disk, just in a little bit different format and location). When a program writes data to disk, it goes through the kernel page cache, to the filesystem layer, to the block layer, and then to disk. The filesystem has to allocate space (which means other writes to disk, updating block allocations, directories, etc.). The blocks are cached in the page cache in case they are read later. If the kernel needs RAM, it can throw them away. tmpfs lives directly in the page cache. So, when a program writes to a tmpfs file, it goes to the page cache and stops. Later, if the kernel needs RAM, it can push those pages to disk (swap space). The only difference between /tmp on disk and tmpfs is when pages get pushed to disk. In a system with sufficient RAM to hold the normal /tmp contents (which aren't very big under most circumstances), they never get pushed to disk with tmpfs, and performance is faster. The only downside to /tmp-on-tmpfs is that it is limited in size, based on available RAM. Ideally, it would be based on swap size, or total RAM+swap, but that's harder to do. However, Fedora defaults to a root filesystem that isn't huge (with a separate /home), so the size of /tmp is still limited. /tmp was never supposed to be about holding arbitrary sized chunks of data. -- Chris Adams <linux@xxxxxxxxxxx> -- users mailing list users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Fedora Code of Conduct: http://fedoraproject.org/code-of-conduct Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines Have a question? Ask away: http://ask.fedoraproject.org
