This is the mail archive of the libc-alpha@sourceware.org mailing list for the glibc project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: [PATCH] log2 and log10 for wordsize-64


On Monday, May 14, 2012 22:00:09 Adhemerval Zanella wrote:
> On 05/14/2012 03:17 PM, Andreas Jaeger wrote:
> > You copied from sysdeps/ieee754/dbl-64 and reformatted the file which
> > makes a diff difficult (unless using -w). Could you send a separate
> > patch that reformats the two files, please?
> 
> Sure, I'm attaching a patch with both e_log2.c and e_log10.c reformatted
> as I did for the wordsize-64 version. I believe now a compare will be
> easier.
> 
> > zero seems to be unused in this code.
> 
> Indeed, I removed it. Also removed it from original source.
> 
> > Please add as comment: two1ln2 = 1/ln2
> 
> Yeah, this remind that using an multiplication to replace a division on
> original code is not the best way to keep accuracy. I get rid of this
> and now the patch is using an division as original code. It shows now
> less performance, but it is still a gain.
> 
> Thanks for the review.
> 
> ---
> 
> These were in my backlog for while. On x86_64 I observed an improvement
> of about 7% for log10 and about 9% for log2. And on PPC64 I observed an
> improvement of about 20% for log10 and about 9% for log2.
> 
> Tested on ppc64 and x86_64.
> 
> ---
> 
> 2012-05-14  Adhemerval Zanella  <azanella@linux.vnet.ibm.com>
> 
> 	* sysdeps/ieee754/dbl-64/wordsize-64/e_log10.c: New file.
> 	* sysdeps/ieee754/dbl-64/wordsize-64/e_log2.c: New file.
> 	* sysdeps/ieee754/dbl-64/e_log10.c: Fixing indents.
> 	* sysdeps/ieee754/dbl-64/e_log2.c: Likewise.

Mention the removal of zero.

Ok with that change.

Andreas
-- 
 Andreas Jaeger aj@{suse.com,opensuse.org} Twitter/Identica: jaegerandi
  SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
   GF: Jeff Hawn,Jennifer Guild,Felix Imendörffer,HRB16746 (AG Nürnberg)
    GPG fingerprint = 93A3 365E CE47 B889 DF7F  FED1 389A 563C C272 A126


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]