[gclist] synchronization cost (was: Garbage collection and XML)

Ji-Yong D. Chung virtualcyber@erols.com
Sat, 10 Mar 2001 16:55:16 -0500


    I am embarassed to admit that, on my prev.
posting, I should have checked my facts before commenting
on spin locks and XCHG.

    After seeing Boehm's email, I ran tests on XCHG,
and I am getting slightly worse results, at about
22 instruction cycles for each XCHG.

    I have run the tests on Pentium II (200 MHZ),
WindowsNT4.0, SP4.  The test is compiled using VC++6.

    The test has to be run multiple times either
with a VC++6.0 profiler or with a timer,
and with minimum no of processes on the
host machine.

||  Here is my code for running the test

#include <iostream.h>
#include <time.h>
#include <sys/timeb.h>

void main()
    struct _timeb    begin,    end;
    int locker = 0;
    int* lock_addr = &locker;


        mov ebx, [lock_addr]
        mov ecx, 10000000


        mov edx, ebx
        mov eax, 1
        xchg eax, [edx]        // Here is the XCHG
        dec ecx
        jnz RETRY


    cout << (end.time - begin.time) * 1000 + end.millitm - begin.millitm <<