This is the mail archive of the glibc-bugs@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]

[Bug math/5769] New: Slow sine function for special values on AMD64


The math sin(double) function is in 64bit distribution (Kubuntu 7.10 AMD64 and
Fedora - unknown version) unreasonable slow (~400 microseconds on Atlon64 X2
4800+!!!) for some special values. In 32bit distribution is everything fine.
I captured some of those values:
0.93340582292648832662962377071381  0x3fedde75e36bb000
2.3328432680770916363144351635128   0x4002a9a9bb38add0
3.7439477503636453548097051680088   0x400df39ae0cdf500
3.9225160069792437411706487182528   0x400f615012801950
4.0711651639931289992091478779912   0x401048df854fdc20
4.7858438478542097982426639646292   0x401324b43fe92fc0
5.9840767662578002727968851104379   0x4017efb1d1df52a0 

For example, this part of code takes a few seconds to complete:

volatile double value = 0.93340582292648832662962377071381;
for(int i=0; i < 10000; i++) {
  volatile double out = sin(value);
}

-- 
           Summary: Slow sine function for special values on AMD64
           Product: glibc
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: math
        AssignedTo: aj at suse dot de
        ReportedBy: grugh at centrum dot cz
                CC: glibc-bugs at sources dot redhat dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=5769

------- You are receiving this mail because: -------
You are on the CC list for the bug, or are watching someone who is.


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