From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael Kerrisk (man-pages)" Subject: Re: [patch] pow.3: Add note on performance characteristics of pow Date: Fri, 17 Oct 2014 07:24:38 +0200 Message-ID: <5440A816.8000002@gmail.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: Sender: linux-man-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: =?windows-1252?Q?Manuel_L=F3pez-Ib=E1=F1ez?= , linux-man-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Cc: mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, GNU C Library List-Id: linux-man@vger.kernel.org Hello Manuel, On 10/17/2014 01:51 AM, Manuel L=F3pez-Ib=E1=F1ez wrote: > Hello, >=20 > This patch documents > https://sourceware.org/bugzilla/show_bug.cgi?id=3D13932 as requested = in > https://sourceware.org/bugzilla/show_bug.cgi?id=3D15267. It would be > nice to add more details, but it seems the behavior and its > consequences is not well understood. The purpose of the note is to > warn users of this behavior and thus avoid frustration > (http://entropymine.com/imageworsener/slowpow/). >=20 > This is my first patch. I followed (hopefully correctly) the instruct= ions here: > https://www.kernel.org/doc/man-pages/patches.html Thanks for this patch. It looks good. But inline patches are easier to = review. One small question below. > diff --git a/man3/pow.3 b/man3/pow.3 > index d0a2ea8..3d2151a 100644 > --- a/man3/pow.3 > +++ b/man3/pow.3 > @@ -320,6 +320,17 @@ The variant returning > also conforms to > SVr4, 4.3BSD, C89. > .SH BUGS > +On 64-bits, > +.\" > +.\" https://sourceware.org/bugzilla/show_bug.cgi?id=3D13932 > +.BR pow () > +may be more than 10,000 times slower for some inputs than for other = nearby I plan to change "some" to "some (rare)". Sound okay? The point is not = to worry people that this is a problem that is commonly encountered. (Or i= s it?) Thanks, Michael > +inputs. The inputs that produce such behavior are different for > +.BR powf (), > +.BR pow () > +and > +.BR powl (). > + > In glibc 2.9 and earlier, > .\" > .\" http://sources.redhat.com/bugzilla/show_bug.cgi?id=3D6776 --=20 Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html