[13:10] hello? [19:06] StyXman: so the problem is to create an efficient readahead list [19:06] we've got an inefficient one today [19:06] replacing that with a differently ineffeicient one doesn't really help things in the long-term [19:06] ideally we'd like to know, on average, which executables request which blocks of which files [19:06] and at what time they do it [19:06] then we can page them into the cache in order, in advance of when they're needed [19:07] are you planning on directly tackling some application problems, similar to this extremely great work done by Behdad: http://mces.blogspot.com/2008/12/improving-login-time-part-3.html ? [19:08] isn't too much low level? I mean, normally booting programs just read a file, maybe seq'ly, maybe randomly, and all you need is to have it already in ram, or do I miss something? [19:08] Mirv: eventually [19:08] StyXman: the page cache works on blocks, not files [19:08] yeah, I know, there is just so many even more low-hanging fruits, while the upstreams might actually fix something too [19:09] Keybuk: again, why so lo level? why not just read the file and let the kernel take care of page cache? [19:09] StyXman: that's what we do today [19:09] if you're low in ram, you can make slices [19:09] Keybuk: ok [19:09] hmm, I could put a mental note somewhere to check whether compiz git fixes the 5s delay (no disk activity) I've seen, it'd good for jaunty if 0.8.0 does not come out [19:09] but we read too much as a result [19:09] in practice, when you execute a binary, you don't read all of it into memory [19:09] you just read certain bits [19:10] Keybuk: how is the read/size ratio? [19:10] I mean, how much do you read? [19:11] StyXman: I don't have numbers on that yet [19:11] Keybuk: ok [19:12] Keybuk: do you know if what readahead does (being so low level) is a consequence of already trying that? how was the approach selected? [19:12] as you can probably tell from the graph changes, my focus atm is on the kernel, udev and modprobe load times [19:12] StyXman: readahead() is just a syscall [19:12] man readahead gives you the docs on it [19:14] Keybuk: ah, ok