Re: [HACKERS] Patch attached...

Hannu Krosing wrote:

> Btw, how did you measure that 30us overhead ?

I measured it with the test program below. With the latest patch it is
no longer 30us, but as far as I can measure 0us.

> Does it involve disk accesses or is it just
> in-memory code that
> speed-concious folks could move to assembly like current
> spinlocking code for some architectures?

For this patch it is an in-memory issue.

--
Chris Bitmead
mailto:chris(at)bitmead(dot)com

#include <stdio.h>
#include <time.h>
#include "libpq-fe.h"

#define rep 1000000

main() {
int c;
PGconn *conn;
PGresult *res;
time_t t, t2;

conn = PQsetdb(NULL,NULL,NULL,NULL,"foo");
time(&t);
for (c = 0; c < rep; c++) {
res = PQexec(conn, "select * from a*");
PQclear(res);
}
time(&t2);
printf("inh %d\n", t2 - t);
time(&t);
for (c = 0; c < rep; c++) {
res = PQexec(conn, "select * from only a");
PQclear(res);
}
time(&t2);
printf("no inh %d\n", t2 - t);

PQfinish(conn);

}