Re: [PATCH v4] sched: automated per session task groups

Valdis.Kletnieks
2010-12-06T00:29:13Z

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On Sat, 04 Dec 2010 15:01:16 EST, Colin Walters said:

> Look around...where? On what basis are you making that claim? I did
> a quick web search for "unix background process", and this tutorial
> (in the first page of Google search results) aimed at grad students
> who use Unix at college definitely describes "nice make":
> http://acs.ucsd.edu/info/jobctrl.shtml

The fact that something is documented doesn't mean the documentation actually
is correct.

There exists a Linux guide written by somebody (who has enough of a rep that
you can safely say "should have known better") who didn't understand the
difference between traditional Unix and Linux, nor what the original concept
was, and it documented the proper way to take a system down quickly as:

# sync;sync;sync;halt

Of course, the *original* was:

# sync
# sync
# sync
# halt

And the whole point of 3 syncs was that the typing time of the second and third
sync's chewed up the time till the first sync finished. Of course, sync;sync
doesn't start the first sync and then make you type. And it overlooked that
the Linux sync is a lot more synchronous than the ATT Unix sync, which returned
as soon as the I/O was scheduled, not completed.

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