Other Parts Discussed in Thread: TDA4VH
Hi, expers:
On tda4vm platform, we found the performance of memcpy become lower after memset zero, test code as follow:
#include <stdio.h>
#include <pthread.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/prctl.h>
#include <sched.h>
#include <signal.h>
#include <string.h>
#include <malloc.h>
unsigned long long DEMO_TST_GetMs()
{
struct timespec time = {0};
clock_gettime(CLOCK_THREAD_CPUTIME_ID, &time);
return (unsigned long long)(time.tv_sec * 1000000 + time.tv_nsec / 1000);
}
int main()
{
int i = 0,j = 0;
unsigned long long lStart = 0;
unsigned long long lEnd = 0;
unsigned long long all = 0;
void *pa = malloc(20 * 1024 * 1024);
void *pb = malloc(20 * 1024 * 1024);
/* do memset ? */
//memset(pa, 0, 20 * 1024 * 1024);
//memset(pb, 0, 20 * 1024 * 1024);
for (j = 0; j < 100; j++)
{
lStart = DEMO_TST_GetMs();
int sum = 0;
for (i = 0; i < 100; i++)
{
sum += i;
memcpy(pa, pb, 20 * 1024 * 1024);
}
lEnd = DEMO_TST_GetMs();
all += lEnd - lStart;
//printf("%lld, %lld\n", lEnd - lStart, all / (j + 1));
}
free(pb);
free(pa);
return 0;
}
Memcpy test without memset, total consume 27 second,(0.16% cache miss of all L1-dcache accesses)
Performance counter stats for 'memcpy_noset':
27379.08 msec task-clock # 0.997 CPUs utilized
3408 context-switches # 0.124 K/sec
1 cpu-migrations # 0.000 K/sec
669 page-faults # 0.024 K/sec
54712024432 cycles # 1.998 GHz
32828016573 instructions # 0.60 insn per cycle
<not supported> branches
418668 branch-misses
39342461969 L1-dcache-loads
61556500 L1-dcache-load-misses # 0.16% of all L1-dcache accesses
26222847268 L1-dcache-stores
27.270167320 seconds time elapsed
27.090683000 seconds user
0.011870000 seconds sys
Memcpy test with memset, total consume 83 second,(0.44% cache miss of all L1-dcache accesses)
Performance counter stats for 'memcpy':
85824.02 msec task-clock # 0.997 CPUs utilized
10882 context-switches # 0.127 K/sec
0 cpu-migrations # 0.000 K/sec
677 page-faults # 0.008 K/sec
171502032179 cycles # 1.998 GHz
32956132885 instructions # 0.19 insn per cycle
<not supported> branches
1252779 branch-misses
39390732794 L1-dcache-loads
171766881 L1-dcache-load-misses # 0.44% of all L1-dcache accesses
26245423599 L1-dcache-stores
84.339231775 seconds time elapsed
83.769493000 seconds user
0.015800000 seconds sys
Thanks
quanli
