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From: Rich Felker <dalias@aerifal.cx>
To: musl@lists.openwall.com
Subject: Re: nice standards complaince issue
Date: Sun, 14 Apr 2013 21:45:10 -0400	[thread overview]
Message-ID: <20130415014510.GS20323@brightrain.aerifal.cx> (raw)
In-Reply-To: <CAK4o1WxJmocyXFSCi7fzYfL4ySxgkzd3P2vzBfNCdKMbtUQDiA@mail.gmail.com>

On Sat, Apr 13, 2013 at 11:23:08PM +0100, Justin Cormack wrote:
> Since glibc 2.2.4, nice() is implemented as a library function that calls
> getpriority(2) to obtain the new nice value to be returned  to  the
>  caller.   With this implementation, a successful call can legitimately
> return -1.  To reliably detect an error, set errno to 0 before the call,
> and check its value when nice() returns -1.

Thanks for the heads-up. Actually, I think there's a much bigger issue
with both nice and setpriority: they're affecting one thread rather
than the process. This may technically not be non-conforming as long
as SCHED_OTHER scheduling is in effect, but it's sketchy. Basically
this all stems from a complete failure of Linux to support process
contention scope and the [PS] option of POSIX... (despite glibc
claiming to support it!)

In any case, the issue you reported should be fixed. Do you have a
proposed patch?

Rich


  reply	other threads:[~2013-04-15  1:45 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-04-13 22:23 Justin Cormack
2013-04-15  1:45 ` Rich Felker [this message]
2013-04-15  7:31   ` Justin Cormack

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