--- Dave Korn <[EMAIL PROTECTED]> wrote: > On 30 March 2006 14:34, Pete wrote: > > > The executable is produced with: > > > > $ make > > g++ -W -Wall -O9 -funroll-loops -mtune=pentium4 > -c > > -o matrix_mult_r.o matrix_mult_r.cc > > Heh. > > > matrix_mult_r.cc:5:19: Timer.h: No such file or > directory > matrix_mult_r.cc: In function `int main()': > matrix_mult_r.cc:20: error: `Timer' undeclared > (first use this function) > matrix_mult_r.cc:20: error: (Each undeclared > identifier is reported only once > for each function it appears in.) > matrix_mult_r.cc:20: error: expected `;' before > "timer" > matrix_mult_r.cc:21: error: `timer' undeclared > (first use this function)
ok... ok... :)
Attaching the files to the email. Hope attachments
are OK.
> However, it's straightforward enough. The default
> thread stack is 1Mb (or
> is it 2, I can't remember off the top of my head).
> Once your stack-based auto
> vars exceed the size of the stack, it go BOOOOOM!
But doesn't the implementation keep track of stack
allocations? Why let the hardware report a SIGSEGV
rather than let libc report "Out of memory" and
killing the process?
> Your problem can be fixed /either/ by making them
> of static storage duration
> (move them out of the function body OR add the
> 'static' qualifier depending on
> scoping considerations),
Trying to learn... Is that because if I declare the
variables as static (or make them global), they're
placed in the "data segment" and the compiler
automatically allocates enough space for them?
> or by using the -Wl,--stack
> flag. Correctly. You
> told ld to provide an 8kB stack. Try 80 meg
> instead, it works a lot beter!
Yes, that definitely did the trick. Thanks! I think
the FAQ should be expanded a bit on the subject (I'd
be willing to write and submit if there's noone
designated as FAQ maintainer).
One last issue. I was replying to one of your earlier
emails about using GDB. For some reason, no matter
what I do, GDB always segfaults when I run the program
under GDB.
For a nice small eigensystem (N=200, ITERATIONS=2000):
$ make
g++ -W -Wall -O9 -funroll-loops -mtune=pentium4 -g
-c -o matrix_mult_r.o matrix_mult_r.cc
g++ -W -Wall -O9 -funroll-loops -mtune=pentium4 -g
-c -o Timer.o Timer.cc
g++ -Wl,--heap,8192,--stack,83886080 -o
matrix_mult_r.exe *.o
$ gdb matrix_mult_r.exe
(gdb) break 1
Breakpoint 1 at 0x401220: file matrix_mult_r.cc, line
1.
(gdb) run
Breakpoint 1, main () at matrix_mult_r.cc:16
16 {
(gdb) n
0x004101f0 in _alloca ()
(gdb) n
Single stepping until exit from function _alloca,
which has no line number information.
0x004101f6 in probe ()
(gdb) n
Single stepping until exit from function probe,
which has no line number information.
0x0041020d in done ()
(gdb) n
Single stepping until exit from function done,
which has no line number information.
main () at matrix_mult_r.cc:16
16 {
(gdb) n
Program received signal SIGSEGV, Segmentation fault.
0x610ae938 in pthread_key_create () from
/usr/bin/cygwin1.dll
I use GDB quite a bit, and would _really_ like to be
able to use in on Cygwin. The problem isn't even with
my benchmarking code. Even with a hello world
program:
#include <iostream>
using namespace std;
int main( void )
{
cout << "hello world" << endl;
return 0;
}
when compiled with:
$ g++ -g foo.cc
produces a segfault under GDB:
$ gdb -quiet a.exe
(gdb) break 1
Breakpoint 1 at 0x401150: file foo.cc, line 1.
(gdb) run
Breakpoint 1, main () at foo.cc:6
6 {
(gdb) n
0x0040f400 in _alloca () at
/usr/lib/gcc/i686-pc-cygwin/3.4.4/include/c++/iostream:77
77 static ios_base::Init __ioinit;
(gdb) n
main () at foo.cc:6
6 {
(gdb) n
Program received signal SIGSEGV, Segmentation fault.
0x610ae938 in pthread_key_create () from
/usr/bin/cygwin1.dll
Also, I noticed from my benchmark code that GDB
reports that it's in libc (or whatever!) functions
like alloca(). Is there a way to surpress mention of
any stepping into functions that don't have debugging
information?
Thanks again,
Pete
__________________________________________________
Do You Yahoo!?
Tired of spam? Yahoo! Mail has the best spam protection around
http://mail.yahoo.com
Makefile
Description: 402397780-Makefile
#define N 600 // The dimension of the matrices
#define ITERATIONS 2000 // Number of times to perform multiplication.
#include "Timer.h"
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
static void complain_and_die( void );
static int getInt( const int low, const int high );
static void fill_matrix( int m[][N] );
static void matrix_multiplication( const int a[][N], const int b[][N], int
result[][N] );
int main( void )
{
// Set up the timer and start it ticking.
Timer timer;
timer.startTimer();
// We multiply m1 and m2, and put the result in m3.
int m1[N][N];
int m2[N][N];
int m3[N][N];
// Seed the random number generator
srand( time(NULL) );
// Perform the multiplication ITERATIONS times.
for ( int i = 0; i < ITERATIONS; ++i )
{
fill_matrix( m1 );
fill_matrix( m2 );
matrix_multiplication( m1, m2, m3 );
}
// Stop the timer and end the program.
timer.endTimer();
timer.printStats();
return 0;
}
inline static void complain_and_die( void )
{
fprintf( stderr, "I need the rank of the matrix\n" );
exit(1);
}
inline static int getInt( const int low, const int high )
{
return low + ( rand() % (high - low + 1) );
}
inline static void fill_matrix( int m[][N] )
{
for ( int i = 0; i < N; ++i )
for ( int j = 0; j < N; ++j )
m[i][j] = getInt(0, 100);
}
inline static void matrix_multiplication( const int a[][N], const int b[][N],
int result[][N] )
{
for( int i = 0; i < N; ++i )
for( int j = 0; j < 3; ++j )
for( int k = 0; k < N ; ++k )
result[i][j] = a[i][k] + b[k][j];
}
#include <iostream>
#include <iomanip>
#include "Timer.h"
using namespace std;
Timer::Timer()
{
}
Timer::~Timer()
{
}
void Timer::startTimer( void )
{
gettimeofday(&t_start, NULL);
this->start = t_start.tv_sec + t_start.tv_usec *
SECONDS_PER_MICROSECOND;
}
void Timer::endTimer( void )
{
gettimeofday(&t_end, NULL);
this->end = t_end.tv_sec + t_end.tv_usec * SECONDS_PER_MICROSECOND;
}
double Timer::getTimeInSeconds( void )
{
return this->end - this->start;
}
// In seconds since the epoch.
//
double Timer::getStartTime( void )
{
return this->start;
}
// In seconds since the epoch.
//
double Timer::getEndTime( void )
{
return this->end;
}
void Timer::printStats( void )
{
streamsize prec = cout.precision();
cout << setprecision(12) << endl << "Timing Stats:" << endl;
// cout << "End: " << this->end << " seconds" << endl;
// cout << "Start: " << this->start << " seconds" << endl;
cout << "Total: " << this->getTimeInSeconds() << " seconds" << endl;
cout << setprecision(prec); // be polite.
}
#ifndef TIMER_H
#define TIMER_H
#include <sys/time.h>
#define SECONDS_PER_MICROSECOND 1.0E-6L;
class Timer
{
private:
timeval t_start, t_end;
double start, end;
public:
Timer::Timer();
Timer::~Timer();
void Timer::startTimer( void );
void Timer::endTimer( void );
double Timer::getTimeInSeconds( void );
double Timer::getStartTime( void );
double Timer::getEndTime( void );
void Timer::printStats( void );
};
#endif
-- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
