From: dave@horsfall.org (Dave Horsfall)
Subject: [TUHS] Sleep()y musings
Date: Wed, 7 Mar 2018 04:58:01 +1100 (EST) [thread overview]
Message-ID: <alpine.BSF.2.21.1803070411380.36136@aneurin.horsfall.org> (raw)
Back when the dinosaurs were using card readers (and yes, I've used a card
reader on Unix; I think it was a desktop CDC model, and the driver would
handle two modes: strict 80-column i.e. one 12-bit column per 16-bit word
and you got 80 of 'em on a DMA channel, or ASCII NL-terminated after last
non-blank column, and no, I have no idea whether it handled EBCDIC or CDC
etc, but I digress as usual).
Where was I? Oh yes, sleeps...
Back when sleep(3) was sleep(2) (yes, Virginia, sleep() used to be a
system call, then it became alarm()/pause(), and now it seems to be
nanosleep(), and I'm wandering again), you never called sleep(1) because
its granularity was +/-1 second (and all the way up to +infinity,
actually, on a really busy machine), thus it could return right away, with
ensuing hilarity.
So, I'm curious:
When did sleep(2) become sleep(3)? Was it V7, or some BSD? Or Babbage
help me, SysVile?
When did the caveat about sleeping for 1 second become known? I don't
think that I ever saw it documented, but was one of those "lore" things
passed around at Unix conferences and the like.
And when did it start using nanosleep() instead of alarm()/pause()? I see
that my Penguin box has a bet both ways; it "may" use SIGALRM[a] (thus
"mixing calls to alarm(2) and sleep() is a bad idea" (well, I've used
both), and also refers to nanosleep().
[a]
Alpine's spell-checker suggested "SICKROOM" here; pretty close when
dealing with timed-out reads on a TTY connection[ii] :-)
[ii]
Have you tried this with Perl? You can't rely on EINTR[3], so you have to
use eval{} blocks instead, and it starts getting pretty fugly...
[3]
And here it suggested "ENTREE".
--
Dave Horsfall DTM (VK2KFU) "Those who don't understand security will suffer."
next reply other threads:[~2018-03-06 17:58 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-06 17:58 Dave Horsfall [this message]
2018-03-08 21:50 ` Dave Horsfall
2018-03-06 18:11 Noel Chiappa
2018-03-06 20:53 ` Clem Cole
2018-03-06 21:39 ` Paul Winalski
2018-03-07 16:33 ` Michael Kjörling
2018-03-07 18:54 ` Paul Winalski
2018-03-08 3:39 Rudi Blom
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