From patchwork Fri Oct 17 13:51:06 2014
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From: =?ISO-8859-1?Q?Manuel_L=F3pez=2DIb=E1=F1ez?= <lopezibanez@gmail.com>
Date: Fri, 17 Oct 2014 15:51:06 +0200
Message-ID: 
 <CAESRpQB5K9U1sBreXUrNa4tPB69cwxC+fdu1bUr5BkU-dtxJMQ@mail.gmail.com>
Subject: Re: [patch] pow.3: Add note on performance characteristics of pow
To: Siddhesh Poyarekar <siddhesh@redhat.com>
Cc: "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>,
	linux-man@vger.kernel.org, GNU C Library <libc-alpha@sourceware.org>

On 17 October 2014 09:58, Siddhesh Poyarekar <siddhesh@redhat.com> wrote:
>> > +inputs. The inputs that produce such behavior are different for
>> > +.BR powf (),
>> > +.BR pow ()
>> > +and
>> > +.BR powl ().
>> > +
>
> The slow fallback is only taken for pow, not powf or powl.

Updated patch inline:

 .\" http://sources.redhat.com/bugzilla/show_bug.cgi?id=6776

and attached in case gmail messes it up.

Cheers,

Manuel.
diff --git a/man3/pow.3 b/man3/pow.3
index d0a2ea8..1b05292 100644
--- a/man3/pow.3
+++ b/man3/pow.3
@@ -320,6 +320,18 @@ The variant returning
 also conforms to
 SVr4, 4.3BSD, C89.
 .SH BUGS
+On 64-bits,
+.\"
+.\" https://sourceware.org/bugzilla/show_bug.cgi?id=13932
+.BR pow ()
+may be more than 10,000 times slower for some (rare) inputs than for other nearby
+inputs.  This only affects 
+.BR pow (),
+and not 
+.BR powf ()
+nor
+.BR powl ().
+
 In glibc 2.9 and earlier,
 .\"
 .\" http://sources.redhat.com/bugzilla/show_bug.cgi?id=6776

diff --git a/man3/pow.3 b/man3/pow.3
index d0a2ea8..1b05292 100644
--- a/man3/pow.3
+++ b/man3/pow.3
@@ -320,6 +320,18 @@ The variant returning
 also conforms to
 SVr4, 4.3BSD, C89.
 .SH BUGS
+On 64-bits,
+.\"
+.\" https://sourceware.org/bugzilla/show_bug.cgi?id=13932
+.BR pow ()
+may be more than 10,000 times slower for some (rare) inputs than for
other nearby
+inputs.  This only affects
+.BR pow (),
+and not
+.BR powf ()
+nor
+.BR powl ().
+
 In glibc 2.9 and earlier,
 .\"