Hi,
I've done some additional very simple minded measurements to estimate
the effects of inling the reference counters and the potential overhead
for checking if we are on a SMP system. I got the following numbers:
I: inlining
NOI: no-inlining
SMPC: SMP check
NOSMPC: no SMP check
Times are in seconds.
NOI/NOSMPC, I/NOSMPC, NOI/SMPC, I/SMPC
P-IV 1800 (single) 7.634 6.892 1.796 0.784
Xeon 3.06GHz (multi) 6.50 4.07 6.67 4.11
Conclusions: Checking for SMP costs about 1% (4.11s vs. 4.07s)
additionally on multi-processor machines, and yields about 880% speed
improvement on older non-HT/non-multiprocessor systems. Inlining is
significant, too. The effect of inlining dwarfs the penalty for checking
for SMP on modern multi-processor systems.
The measurements were done with the simple benchmark attached, they are
of course no substitute for doing some real profiling with the office code.
Heiner
--
Jens-Heiner Rechtien
[EMAIL PROTECTED]
CFLAGS= -I. -fPIC -O2 -Wall -DINLINE -DCHECKSMP
#CFLAGS= -I. -fPIC -O2 -Wall -DINLINE
#CFLAGS= -I. -fPIC -O2 -Wall -DCHECKSMP
#CFLAGS= -I. -fPIC -O2 -Wall
intrlock: intrlock.o libsal.so
$(CC) $(CFLAGS) -o intrlock $< -L. -lsal
libsal.so: sal.o
$(CC) -shared -o libsal.so $<
clean:
rm *.o libsal.so intrlock
all: intrlock libsal.so
extern int is_smp;
#if defined(INLINE)
#if defined(CHECKSMP)
inline int incrementInterlockedCount(int *p) {
int n;
if ( is_smp ) {
__asm__ __volatile__ (
"movl $1, %0\n\t"
"lock\n\t"
"xaddl %0, %2\n\t"
"incl %0" :
"=&r" (n), "=m" (*p) :
"m" (*p) :
"memory");
}
else {
__asm__ __volatile__ (
"movl $1, %0\n\t"
"xaddl %0, %2\n\t"
"incl %0" :
"=&r" (n), "=m" (*p) :
"m" (*p) :
"memory");
}
return n;
}
#else /* !CHECKSMP */
inline int incrementInterlockedCount(int *p) {
int n;
__asm__ __volatile__ (
"movl $1, %0\n\t"
"lock\n\t"
"xaddl %0, %2\n\t"
"incl %0" :
"=&r" (n), "=m" (*p) :
"m" (*p) :
"memory");
return n;
}
#endif /* !CHECKSMP */
#else /* INLINE */
int incrementInterlockedCount(int *p);
#endif /* INLINE */
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