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[TESTS] add new methods in ip-hash test file

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added methods to provide a better hash with small input sets
This commit is contained in:
Willy Tarreau 2008-04-13 09:27:00 +02:00
parent 53cfa0e58d
commit a532324128
1 changed files with 19 additions and 5 deletions
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24
tests/ip-hash.c
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@ -84,6 +84,7 @@ uint32_t hash_tw3(uint32_t a)
* About 0x50 bytes, 6 shifts.
*/
int counts_bj6[NSERV][NSERV];
int counts_bj6x[NSERV][NSERV];
uint32_t hash_bj6(uint32_t a)
{
a = (a+0x7ed55d16) + (a<<12);
@ -100,6 +101,7 @@ uint32_t hash_bj6(uint32_t a)
* About 0x40 bytes, 7 shifts.
*/
int counts_bj7[NSERV][NSERV];
int counts_bj7x[NSERV][NSERV];
uint32_t hash_bj7(uint32_t a)
{
a -= (a<<6);
@ -134,7 +136,8 @@ void dump_hash_results(char *name, int counts[NSERV][NSERV]) {
for (srv = 0; srv <= nsrv; srv++) {
err = 100.0*(counts[nsrv][srv] - (double)counts[0][0]/(nsrv+1)) / (double)counts[0][0];
//printf("%6d ", counts[nsrv][srv]);
printf("% 3.1f%% ", err);
printf("% 3.1f%%%c ", err,
counts[nsrv][srv]?' ':'*'); /* display '*' when a server is never selected */
err = fabs(err);
total_err += err;
if (err > max_err)
@ -142,7 +145,7 @@ void dump_hash_results(char *name, int counts[NSERV][NSERV]) {
}
total_err /= (double)(nsrv+1);
for (srv = nsrv+1; srv < NSERV; srv++)
printf(" ");
printf(" ");
printf(" avg_err=%3.1f, max_err=%3.1f\n", total_err, max_err);
}
printf("\n");
@ -160,10 +163,13 @@ int main() {
memset(counts_bj6, 0, sizeof(counts_bj6));
memset(counts_bj7, 0, sizeof(counts_bj7));
mask = 0xFFF00F00; // user mask to apply to addresses
for (nr = 0; nr < 100000; nr++) {
address += ~nr; // semi-random addresses.
address = 0x10000000;
mask = 0xffffff00; // user mask to apply to addresses
for (nr = 0; nr < 0x10; nr++) {
//address += ~nr; // semi-random addresses.
//address += 1;
address += 0x00000100;
//address += 0x11111111;
//address += 7;
//address += 8;
//address += 256;
@ -176,6 +182,12 @@ int main() {
count_hash_results(hash_tw3(address & mask), counts_tw3); // 1.01s / 100M
count_hash_results(hash_bj6(address & mask), counts_bj6); // 1.07s / 100M
count_hash_results(hash_bj7(address & mask), counts_bj7); // 1.20s / 100M
/* adding the original address after the hash reduces the error
* rate in in presence of very small data sets (eg: 16 source
* addresses for 8 servers). In this case, bj7 is very good.
*/
count_hash_results(hash_bj6(address & mask)+(address&mask), counts_bj6x); // 1.07s / 100M
count_hash_results(hash_bj7(address & mask)+(address&mask), counts_bj7x); // 1.20s / 100M
}
dump_hash_results("hash_id", counts_id);
@ -183,6 +195,8 @@ int main() {
dump_hash_results("hash_tw2", counts_tw2);
dump_hash_results("hash_tw3", counts_tw3);
dump_hash_results("hash_bj6", counts_bj6);
dump_hash_results("hash_bj6x", counts_bj6x);
dump_hash_results("hash_bj7", counts_bj7);
dump_hash_results("hash_bj7x", counts_bj7x);
return 0;
}