[ARM] Multi-core optimization test...

Domain/ARM 2011.05.03 11:42

This test is done under following environment.

x86 :

intel Core(TM)2 Duo T9400 2.53Mhz
GCC-4.4.5

ARM :

OMAP4430 (Cortax-A9)
Android NDK platform 9

Test code.

/*
 * Test Configuration
 */
#define _ARRSZ    1024*1024*8

static int _arr[_ARRSZ];

static void
_init() {
    int i;
    for (i = 0; i < _ARRSZ; i++)
        _arr[i] = i;
}

static unsigned long long
_utime() {
    struct timeval tv;
    if (gettimeofday(&tv, NULL))
        assert(0);
    return (unsigned long long)(tv.tv_sec * 1000000)
        + (unsigned long long)tv.tv_usec;
}

#define _test_arraycopy_pre()               \
    int  i;                                 \
    unsigned long long ut;                  \
    int* ia = malloc(_ARRSZ * sizeof(*ia));

#define _test_arraycopy_post()              \
    free(ia);

#define _operation()            \
    do {                        \
        ia[i] = _arr[i];        \
    } while (0)

static void*
_test_arraycopy_worker(void* arg) {
    int     i;
    int*    ia = arg;
    for (i = (_ARRSZ / 2); i < _ARRSZ; i++)
        _operation();
    return NULL;
}

static unsigned long long
_test_arraycopy_sc() {
    _test_arraycopy_pre();

    ut = _utime();
    for (i = 0; i < _ARRSZ; i++)
        _operation();
    ut = _utime() - ut;

    _test_arraycopy_post();

    return ut;
}

static unsigned long long
_test_arraycopy_dc() {
    pthread_t thd;
    void*     ret;
    _test_arraycopy_pre();

    ut = _utime();
    if (pthread_create(&thd,
               NULL,
               &_test_arraycopy_worker,
               (void*)ia))
        assert(0);

    for (i = 0; i < (_ARRSZ / 2); i++)
        _operation();

    if (pthread_join(thd, &ret))
        assert(0);

    ut = _utime() - ut;

    _test_arraycopy_post();

    return ut;
}

#undef _test_arraycopy_pre
#undef _test_arraycopy_post

int
main(int argc, char* argv[]) {
    _init();
    printf(">> SC : %lld ", _test_arraycopy_sc());
    printf(">> DC : %lld\n", _test_arraycopy_dc());
    return 0;
}

[Test 1]
x86

>> SC : 59346 >> DC : 38566
>> SC : 59195 >> DC : 39028
>> SC : 49529 >> DC : 38160
>> SC : 49722 >> DC : 38457
>> SC : 49952 >> DC : 37457

ARM

>> SC : 102295 >> DC : 94147
>> SC : 102264 >> DC : 94025
>> SC : 102173 >> DC : 94116
>> SC : 102172 >> DC : 94116
>> SC : 102325 >> DC : 94177

Change '_operation' macro to as follows

#define _operation()                                    \
    do {                                                \
        if (i > _ARRSZ / 2)                             \
            ia[i] = (_arr[i] & 0xff) << 8 ^ _arr[i];    \
        else                                            \
            ia[i] = (_arr[i] & 0xff) << 16 ^ _arr[i];   \
    } while (0)                                         \

[Test 2]
x86

>> SC : 60696 >> DC : 40523
>> SC : 56907 >> DC : 45355
>> SC : 55066 >> DC : 42329
>> SC : 54931 >> DC : 40651
>> SC : 57022 >> DC : 41879

ARM

>> SC : 164514 >> DC : 112671
>> SC : 163971 >> DC : 112854
>> SC : 164521 >> DC : 112976
>> SC : 163940 >> DC : 112732
>> SC : 164245 >> DC : 112671

Interesting result, isn't it?
For heavily-memory-accessing-code (Test 1), ARM does not show good statistics for multi-core (in this case, dual-core) optimization.
But, if not (Test 2), optimization shows quite good results.
And, x86 seems to handle memory accessing from multi-core, quite well.

So, developers should consider ARM's characteristic when optimize codes for multi-core.
(I'm sure that ARM will improve this someday! :-) )

* Things to consider regarding this kind of optimization *
Cache, Cache coherence, Memory Controller, Bus etc...

[ Test for later version of ARM (ex Cortax-A15) will be listed continuously... ]

신고

'Domain > ARM' 카테고리의 다른 글

[ARM] Multi-core optimization test...  (0) 2011.05.03
[ARM] Sample code for unwinding stack with DWARF2 information.  (0) 2010.04.07
[ARM] Sample code for unwinding stack in Thumb mode.  (0) 2010.04.07
[ARM] Unwinding Stack.  (0) 2009.09.15
[ARM] Long jump.  (0) 2007.06.05
[ARM] .init_array section  (0) 2007.03.18
tags : ,
Trackback 0 : Comment 0

티스토리 툴바