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Re: The state of glibc libm
- From: James Cloos <cloos at jhcloos dot com>
- To: "Joseph S. Myers" <joseph at codesourcery dot com>
- Cc: libc-alpha at sourceware dot org, gcc at gcc dot gnu dot org, Geert Bosch <bosch at adacore dot com>, Christoph Lauter <christoph dot lauter at lip6 dot fr>
- Date: Thu, 15 Mar 2012 14:03:19 -0400
- Subject: Re: The state of glibc libm
- Copyright: Copyright 2012 James Cloos
- Openpgp: ED7DAEA6; url=http://jhcloos.com/public_key/0xED7DAEA6.asc
- Openpgp-fingerprint: E9E9 F828 61A4 6EA9 0F2B 63E7 997A 9F17 ED7D AEA6
- References: <Pine.LNX.4.64.1202291655580.7156@digraph.polyomino.org.uk><20120314143045.GG3804@xvii.vinc17.org><Pine.LNX.4.64.1203141432400.22094@digraph.polyomino.org.uk><20120315020743.GH3804@xvii.vinc17.org>
>>>>> "VL" == Vincent Lefevre <vincent+gcc@vinc17.org> writes:
VL> sinf being slower than sin is surprising
Some weeks back I wrote a simple app to output a couple of waveforms as
float samples (I encased it in a tiny script which piped the output to
sox to create a wav). I found that converting it to work on and output
doubles improved performance from around 2.2 sec per minute of output to
around 0.3 sec per minute for a simple tan(sin(t)) waveform.
That is using glibc-2.14.1 on amd64 on a 2800MHz K10, compiled with
gcc-4.6.2 with -O2 and the graphite -floop-... options.
Some improvements have landed for the float versions of libm since.
-JimC
--
James Cloos <cloos@jhcloos.com> OpenPGP: 1024D/ED7DAEA6