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Full Discussion: Weird timing results in C
Top Forums Programming Weird timing results in C Post 302352644 by jim mcnamara on Saturday 12th of September 2009 01:54:05 PM
Old 09-12-2009
With regard to static functions:
I assume this is because the C99 standard says little about implemention of static text other than scope changes -

In large single file programs with a lot of static functions mixed in with auto functions -
I've encounteered really obscure problems in gcc 3.1, cc on HP UX 11.1. For example an auto function not being executed at all. Sounds odd, but it is true. The same "inherited program design" also screwed up optimizations by forcing the complier to make decisions it was not expected to make - according the HP compiler team anyway.

Basically to resolve the problems I had to completely turn off optimzation, and declare all functions static to get correct results. Since a fixed makefile was a requirement for the entire app suite, this meant a big rewrite for several very large programs.

Your problem is nothing like that. It almost HAS to be cache-related Based on what you said about your hardware, if you were to chunk your 125MB of data into 21 ~6MB chunks, then iterate (1,2,3) over each subset chunk the problem would not be there. If it is cache related - and with no other observations to work on that would be my guess.
 

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SoDebug(3)							       Coin								SoDebug(3)

NAME
SoDebug - SYNOPSIS
#include <SoDebug.h> Static Public Member Functions static const char * GetEnv (const char *var) static void RTPrintf (const char *formatstr,...) static void NamePtr (const char *name, void *ptr) static const char * PtrName (void *ptr) static void write (SoNode *node) static void writeToFile (SoNode *node, const char *filename) static void writeField (SoField *field) static void printName (SoBase *base) Detailed Description The SoDebug class is a small collection of debugging-related functions. Member Function Documentation const char * SoDebug::GetEnv (const char *var) [static] This is a portable getenv-wrapper. See also: coin_getenv() void SoDebug::RTPrintf (const char *formatstr, ...) [static] Real-time printf designed for use when use of standard printf() would cause timing problems. NOT IMPLEMENTED. Currently it just forwards to printf(). void SoDebug::NamePtr (const char *name, void *ptr) [static] Associate a name with an arbitrary pointer. You can fetch the name of the pointer later with PtrName(). See also: PtrName() const char * SoDebug::PtrName (void *ptr) [static] Returns the name set on a pointer with NamePtr(). If no name has been set, '<unnamed>' is returned. See also: NamePtr() void SoDebug::write (SoNode *node) [static] Writes the node to stdout. void SoDebug::writeToFile (SoNode *node, const char *filename) [static] Writes the node to the given filename, or /tmp/debug.iv if filename is NULL. void SoDebug::writeField (SoField *field) [static] Not implemented. void SoDebug::printName (SoBase *base) [static] Not implemented. Author Generated automatically by Doxygen for Coin from the source code. Version 3.1.3 Wed May 23 2012 SoDebug(3)
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