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<TITLE> [Mono-bugs] [Bug 644699] New: System.Math functions 2x slower than libc
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<H1>[Mono-bugs] [Bug 644699] New: System.Math functions 2x slower than libc</H1>
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<B>bugzilla_noreply at novell.com</B>
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<A HREF="mailto:mono-bugs%40lists.ximian.com?Subject=%5BMono-bugs%5D%20%5BBug%20644699%5D%20New%3A%20System.Math%20functions%202x%20slower%20than%0A%09libc&In-Reply-To="
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TITLE="[Mono-bugs] [Bug 644699] New: System.Math functions 2x slower than libc">bugzilla_noreply at novell.com
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<I>Thu Oct 7 13:41:13 EDT 2010</I>
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<PRE>
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<A HREF="https://bugzilla.novell.com/show_bug.cgi?id=644699">https://bugzilla.novell.com/show_bug.cgi?id=644699</A>
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<A HREF="https://bugzilla.novell.com/show_bug.cgi?id=644699#c0">https://bugzilla.novell.com/show_bug.cgi?id=644699#c0</A>
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Summary: System.Math functions 2x slower than libc
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Classification: Mono
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Product: Mono: Class Libraries
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Version: 2.8.x
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Platform: i686
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OS/Version: All
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Status: NEW
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Severity: Enhancement
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Priority: P5 - None
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Component: System
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AssignedTo: <A HREF="http://lists.ximian.com/mailman/listinfo/mono-bugs">mono-bugs at lists.ximian.com</A>
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ReportedBy: <A HREF="http://lists.ximian.com/mailman/listinfo/mono-bugs">jonathan.shore at gmail.com</A>
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QAContact: <A HREF="http://lists.ximian.com/mailman/listinfo/mono-bugs">mono-bugs at lists.ximian.com</A>
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Found By: ---
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Blocker: ---
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Created an attachment (id=393626)
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--> (<A HREF="http://bugzilla.novell.com/attachment.cgi?id=393626">http://bugzilla.novell.com/attachment.cgi?id=393626</A>)
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C++ and C# code for 2 variants of benchmark
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Description of Problem:
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Benchmarks such as the "language shootout" nbody problem highlight a severe
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peformance problem with regard to fundamental numerical routines (such as
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Sqrt). In tests the mono implementation of Sqrt is 2x slower than libc or JVM
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implementations. libc uses MMX instructions in many cases and I believe that
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the mono implementation does not
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Other math functions in System.Math should also be inspected for their relative
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performance to libc. Suggest the build option or default to map many of the
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System.Math functions to libc calls short of a comparably performant
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implementation in Mono directly.
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Steps to reproduce the problem:
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1. Run nbody benchmark on 64 bit linux box g++ version vs mono C#
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implementation
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2. Run for 500 miilion iterators for fair comparison
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2. Observe that C++ implementation 2x as fast
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3. change calls to Math.Sqrt and sqrt() in C++ implementation to alternate
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inlined implementation
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4. Observe that the performance of the 2 programs is 1:1 with an alternate
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impl.
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Actual Results:
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191 seconds for mono run
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92 seconds c++ run
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Expected Results:
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~100 seconds for each
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How often does this happen?
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Additional Information:
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--
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Configure bugmail: <A HREF="https://bugzilla.novell.com/userprefs.cgi?tab=email">https://bugzilla.novell.com/userprefs.cgi?tab=email</A>
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------- You are receiving this mail because: -------
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You are the QA contact for the bug.
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You are the assignee for the bug.
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</PRE>
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