| sadmac | Keybuk: good morning | 10:19 |
|---|---|---|
| Keybuk | morning | 10:19 |
| Keybuk | happy new year | 10:19 |
| sadmac | Keybuk: you too | 10:20 |
| sadmac | Keybuk: just pushed events-related code to my state machine prototype | 10:21 |
| sadmac | Keybuk: so what's up with that secret kernel patch? :) | 10:21 |
| ion_ | I want to know, too | 10:23 |
| Keybuk | I posted it to lkml already | 10:24 |
| Keybuk | http://lkml.org/lkml/2008/12/27/80 | 10:24 |
| Keybuk | (patch is in my in-reply-to message) | 10:25 |
| sadmac | Keybuk: ah. I misthunderbirded | 10:29 |
| Keybuk | misthunderbirded? | 10:29 |
| Keybuk | v. to use the wrong mail client | 10:30 |
| Keybuk | ? :p | 10:30 |
| sadmac | probably the case | 10:30 |
| * Keybuk likes the fact the objections to that patch all come from @redhat.com :p | 10:30 | |
| sadmac | Keybuk: well it is lkml :P | 10:30 |
| Keybuk | as I keep pointing out, if we do so well, you guys give up - we're *screwed*! :p | 10:31 |
| sadmac | heh. | 10:31 |
| sadmac | Keybuk: well, now that I've implemented large chunks of the state machine, I've found it to be even less quirky and more simple than I thought. | 10:34 |
| sadmac | I've been able to nudge out a lot of the semi-strange behavior. | 10:34 |
| Keybuk | you've been working during the break, haven't you? :p | 10:38 |
| Keybuk | that's naughty | 10:38 |
| sadmac | Keybuk: well, I became almost totally noctournal. Nobody's around to party with between 3 and 7am | 10:39 |
| Keybuk | odd | 10:39 |
| Keybuk | I returned to something like normal UK waking hours | 10:39 |
| sadmac | heh | 10:40 |
| soren | Keybuk: I'm looking at that patch, and can't help but wonder if there's a mechanism for reparenting a process to a different process than pid 1? | 10:45 |
| sadmac | soren: check the clone() manpage. I almost want to say I saw something like that in there | 10:45 |
| sadmac | I might be thinking of the option to signal the parent with something other than sigchld though | 10:46 |
| sadmac | the most fun part of my waitfd patch: read returns ECHILD | 10:47 |
| sadmac | took a bit to convince myself that was legal | 10:47 |
| soren | Keybuk: I understand that if it only works for init, the code would just never be triggered if another process has done the PR_SET_ADOPTSIG thing, and that there's no particular reason to hardcode anything like that, but still it left me wondering. | 10:47 |
| Keybuk | it's the same mechanism | 10:47 |
| Keybuk | that's why the 1 isn't hardcoded, but uses a child_reaper variable | 10:47 |
| Keybuk | you'd generally not use SIGCHLD for that notification, since they're not queued | 10:48 |
| Keybuk | you'd use SIGRTMIN+n | 10:48 |
| soren | I don't think I get it. How can a process other than init adopt a process? | 10:52 |
| * sadmac wonders what happens if you clone with CLONE_PARENT from init... | 10:54 | |
| Keybuk | soren: you're forgetting that in Linux, threads are just processes :p | 11:50 |
| Keybuk | so when a thread parent dies, it's reparented to another thread in the same group, not init | 11:50 |
| Keybuk | sadmac: init's ppid is 1, so nothing - you get a child of init | 11:51 |
| sadmac | Keybuk: I was goig to mention that, but I think he wanted to know if there was a way to explicitly set where a child will be reparented | 11:51 |
| sadmac | Keybuk: ah | 11:51 |
| sadmac | Keybuk: what about unices like (I think) HPUX that display a system_idle process with pid 0 | 11:52 |
| sadmac | does that not appear as the parent of anything? | 11:52 |
| Keybuk | does HPUX even have clone() ? :p | 11:53 |
| sadmac | nobody has clone | 11:53 |
| sadmac | that's just us | 11:53 |
| Keybuk | so who cares? :p | 11:53 |
| sadmac | someone at HP I'd imagine | 11:53 |
| Keybuk | Upstart doesn't work on HPUX, so EOFFTOPIC :p | 11:54 |
| sadmac | Linux also has a system idle process of a kind I believe, but it doesn't appear in ps. | 11:54 |
| sadmac | it may not be a "process" of any real sort. | 11:54 |
| Keybuk | actually, I'm lying | 11:55 |
| Keybuk | init has a ppid of 0 | 11:55 |
| sadmac | ah. thought so | 11:55 |
| sadmac | graphs with loops feels very un-unix | 11:55 |
| Keybuk | Linux has kernel threads, they are all children of kthreadd | 11:55 |
| Keybuk | which is pid=2, ppid=0 | 11:55 |
| sadmac | ah | 11:57 |
| Keybuk | we looked | 12:00 |
| Keybuk | summary | 12:00 |
| Keybuk | "Don't do that then" | 12:00 |
| Keybuk | it'd be ok until the clone exited, at which point you'd maybe get an OOPS or a PANIC :) | 12:00 |
| sadmac | add that to the list of "things to make an intern patch when you're bored" | 12:01 |
| sadmac | yeah, I could see that reading as an init crash | 12:02 |
| sadmac | There's something kind of sad about all of APL being in unicode | 12:06 |
| sadmac | not quite as sad as the klingon alphabet, but still... | 12:06 |
| Keybuk | APL? | 12:08 |
| sadmac | Keybuk: "A Programming Language" | 12:09 |
| Keybuk | what's wrong with unicode? | 12:09 |
| sadmac | Keybuk: there's nothing wrong with unicode per se | 12:09 |
| sadmac | Keybuk: APL has no textual commands | 12:09 |
| sadmac | Keybuk: its all symbols. some greek ones, some not even in any alphabet | 12:10 |
| Keybuk | ah, how silly | 12:10 |
| sadmac | Keybuk: its the esoteric programming language that saw production time | 12:10 |
| sadmac | Enterprise Brainfuck | 12:10 |
| sadmac | Keybuk: it was reeeeely good at matrix operations, which was good for getting certain tasks done in a hurry. | 12:11 |
| sadmac | http://en.wikipedia.org/wiki/File:LifeInApl.gif | 12:11 |
| sadmac | ^^conway's game of life | 12:11 |
| Keybuk | does it use the Unicode Interrobang character as an exception operator? | 12:11 |
| sadmac | dunno. It predates unicode by about 30 years, so it wouldn't have drawn the inspiration from there | 12:12 |
| Keybuk | n < 2 → ⁈ | 12:13 |
| ion_ | That’s not an interrobang. | 12:13 |
| sadmac | N is less than 2 implies WTF | 12:13 |
| Keybuk | 1 + 1 ≠ 2 → ‼ | 12:13 |
| Keybuk | ion_: yes it is? | 12:13 |
| ion_ | ‽ | 12:14 |
| sadmac | ⸘ | 12:14 |
| sadmac | where is your god now? | 12:14 |
| Keybuk | ah, right | 12:14 |
| Keybuk | we can use utf-8 in C now, right ? | 12:15 |
| ion_ | What i still don’t know is why Unicode has white smiling and frowning face, but only a black smiling face. | 12:15 |
| ion_ | faces | 12:15 |
| sadmac | ion_: I blogged on this once | 12:15 |
| ion_ | Oh | 12:16 |
| sadmac | ion_: http://screwyouenterpriseedition.blogspot.com/2008/02/worst-of-unicode.html | 12:16 |
| ion_ | Yeah, just found it with google. | 12:17 |
| Keybuk | most of Unicode's symbol characters are inherited from other standard sets | 12:17 |
| Keybuk | I mean | 12:18 |
| Keybuk | you're talking about a character set that has an entire code block reserved for "Byzantine Musical Symbols" and you're complaining about its smiley faces | 12:19 |
| sadmac | Keybuk: I believe I did mention the klingon alphabet earlier | 12:19 |
| sadmac | Keybuk: and there are musical instrument companies open today that were around during the byzantine empire | 12:19 |
| sadmac | (World's oldest corporation: Zildjian) | 12:20 |
| Keybuk | Unicode doesn't have space for Klingon | 12:21 |
| Keybuk | that's nowhere near the oldest company! | 12:22 |
| Keybuk | there are European breweries older than that! :p | 12:23 |
| sadmac2 | Keybuk: when does fork return EBUSY? | 12:39 |
| sadmac2 | or whatever equates to Resource temporarily unavailable | 12:39 |
| Keybuk | memory limits, process limits, etc. | 12:40 |
| sadmac2 | hmm | 12:41 |
| sadmac2 | left my workstation running over the break | 12:41 |
| sadmac2 | and my login session appears to be unwell | 12:42 |
| sadmac2 | heh, the whole python state machine is 390 lines | 12:46 |
| sadmac2 | I have a real desk now! | 14:29 |
| sadmac2 | Keybuk: what do you think the interface for waitfd should look like? | 14:31 |
| Keybuk | waitfd(flags) | 14:33 |
| Keybuk | gives you an fd | 14:33 |
| Keybuk | you read() something like siginfo_t with all the expanded status information | 14:33 |
| sadmac2 | Keybuk: its more the list of pids to wait on that concerns me | 14:34 |
| Keybuk | how do you mean? | 14:35 |
| sadmac2 | Keybuk: do you always want to wait on /all/ children with waitfd, or do you want some of the selection power that you have with waitpid&co | 14:36 |
| sadmac2 | Keybuk: and if so, what replaces the wait on just one process mechanic? it doesn't make much sense for this case | 14:36 |
| sadmac2 | but waiting on a few specific ones might | 14:36 |
| Keybuk | I figured you'd use something like the waitid() syntax | 14:37 |
| Keybuk | waitfd (P_PID, pid, 0) | 14:37 |
| Keybuk | waitfd (P_ALL, 0, WEXITED | WSTOPPED) | 14:38 |
| Keybuk | type thing | 14:38 |
| Keybuk | but then I'm about the only person in the world who even knows about waitid() :p | 14:38 |
| sadmac2 | Keybuk: yes, but say I want to wait on pid 3, 4, and 7, but not 5,6,whatever else | 14:38 |
| Keybuk | fd = waitfd (-1, P_PID, 6, WEXITED); | 14:41 |
| Keybuk | err | 14:41 |
| Keybuk | fd = waitfd (-1, P_PID, 3, WEXITED); | 14:41 |
| Keybuk | waitfd (fd, P_PID, 4, WEXITED); | 14:41 |
| Keybuk | waitfd (fd, P_PID, 7, WEXITED); | 14:41 |
| Keybuk | ? | 14:41 |
| Keybuk | signalfd-style? | 14:41 |
| sadmac2 | Keybuk: if that's ok with everyone | 14:41 |
| sadmac2 | Keybuk: right now it has waitpid's signature | 14:42 |
| Keybuk | I don't really like the whole "read an int and figure it out" type approach | 14:43 |
| Keybuk | that int is squashed from a siginfo_t-style struct in the first place | 14:43 |
| Keybuk | why not just read that struct? | 14:43 |
| sadmac2 | Keybuk: I didn't use waitid because it doesn't return a different status if it errors out due to WNOHANG, so you have to zero the return struct and then test | 14:44 |
| sadmac2 | Keybuk: and I need to check this from /inside/ the kernel in places. | 14:44 |
| sadmac2 | Keybuk: but I think all of this was in the name of not having to add crap to exit.c, and I think I've had to do that already anyway | 14:44 |
| sadmac2 | there goes my laptop | 14:46 |
| sadmac2 | IRC > Nagios | 14:46 |
| Keybuk | sadmac2: err, isn't the point that read() returns you that status now ? :P | 14:48 |
| sadmac2 | Keybuk: poll() was the issue | 14:48 |
| Keybuk | you don't *have* a WNOHANG flag with waitfd | 14:48 |
| Keybuk | instead you make the socket blocking/non-blocking | 14:48 |
| Keybuk | and read() returns EAGAIN | 14:48 |
| sadmac2 | Keybuk: I use WNOHANG for poll | 14:48 |
| Keybuk | why? | 14:49 |
| sadmac2 | Keybuk: check if something exited with WNOHANG+WNOWAIT. If it didn't, poll_wait, if it did, return | 14:49 |
| Keybuk | oh, I see | 14:52 |
| sadmac2 | Keybuk: you do have a WNOHANG flag with waitfd | 15:10 |
| sadmac2 | Keybuk: WNOHANG == O_NONBLOCK | 15:10 |
| sadmac2 | I've allowed it, and its cheap enough that I'm going to keep on allowing it | 15:11 |
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