Hey cee1, cee1 [2015-05-18 23:52 +0800]: > At the first glance, I find ureadahead has some difference compared > with the readahead once in systemd, IIRC:
Yes, for sure. systemd's was improved quite a bit. ureadahead is mostly unmaintained, but it works well enough so we didn't bother to put work into it until someone actually complains :-) > 1. ureadahead.service is in default.target, which means ureadahead > starts later than systemd's? That mostly means that it's not started with e. g. emergency or rescue. It still starts early (DefaultDependencies=false). > 2. The original systemd readahead has "collect" and "replay" two > services, and these are done in ureadahead.service? Yes. > 3. IIRC, The original systemd readahead uses madvise(); ureadahead > uses readahead() > 4. The original systemd readahead uses fanotify() to get the list of > accessed files; ureadahead use fsnotify I haven't verified these, but this sounds correct. ureadahead is really old, presumably the newer features like fanotify weren't available back then. > 5. ureadahead has different readahead strategies for ssd and hhd: Right. These were created by some rather wide-scale measurements back then. Martin -- Martin Pitt | http://www.piware.de Ubuntu Developer (www.ubuntu.com) | Debian Developer (www.debian.org) _______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel