Ok about the patches : there had to be a reason for those not to be merged upstream. Some of my co-workers noticed the performance improvement when binding values between -pi and pi but the thing is, this kind of trick do not need to be applied when on 32 bits systems... Libm's behavior is not really arch-proof in terms of performance which is a bit confusing (and I would expect 64 bit being better than 32 bits when dealing with maths... :( Have you tried pushing your code upstream ? Maybe this would be useful for future versions.
Thanks for your help Jerome On Sunday 07 March 2010, Aurelien Jarno wrote: > On Sun, Mar 07, 2010 at 07:43:46PM +0100, Jerome Vizcaino wrote: > > Hi, > > > > I could not say for sure the difference between sin and sinf (for > > example) on Suse but the performance ratio I had on 32 bits, stayed the > > same on 64 bits. This is why I was surprised to get impressive slowness > > when moving to debian :( Thanks for pointing out the Suse patch : as we > > only have Suse or Debian at work I could not do more comparisons. > > > > How about including patches from OpenSuse ? Is it possible as a quick > > workaround? > > The patches from OpenSuse are ugly and very invasive, and they do not > seem to include the recent errno changes for C99 compliance (though I > haven't tested them). I am not really sure we want that. I have started > to rewrite part of the functions in assembly. > > While this new assembly code behaves correctly with your testcase, it is > twice slower than the current version when using normal arguments. I > have modified a bit your code to stay within a reasonable range of > arguments, and also test the l version of the functions. > > Here is the result with the original code (using C code for the f > > version): > | Testing 10000000 sinf, cosf and tanf... Result: 19764686.000000, > | Duration: 0.516700 sec Testing 10000000 sin, cos and tan (with float > | args)... Result: 19764686.000000, Duration: 1.056214 sec Testing 10000000 > | sinl, cosl and tanl (with float args)... Result: 19764686.000000, > | Duration: 1.089871 sec > > Here is the result with assembly code instead (using the FPU > > instructions), I get instead: > | Testing 10000000 sinf, cosf and tanf... Result: 19764686.000000, > | Duration: 1.010248 sec Testing 10000000 sin, cos and tan (with float > | args)... Result: 19764686.000000, Duration: 1.055434 sec Testing 10000000 > | sinl, cosl and tanl (with float args)... Result: 19764686.000000, > | Duration: 1.095374 sec > > As I expect most codes to use values between -2pi and 2pi, I am not > really sure we should change the current code. > -- To UNSUBSCRIBE, email to debian-glibc-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/201003080017.41964.vizcaino_jer...@yahoo.fr
