Re: LWLock contention: I think I understand the problem

> I guess what really bothers me now is why the select() in 7.1 wasn't
> slower than it was. We made 7.2 especially for multicpu systems, and
> here we have identical performance to 7.1. Tatsuo, is AIX capable of
> <10 millisecond sleeps? I see there is such a program in the archives
> from Tom Lane:
>
> http://fts.postgresql.org/db/mw/msg.html?mid=1217731
>
> Tatsuo, can you run that program on the AIX box and tell us what it
> reports? It would not surprise me if AIX supported sub-10ms select()
> timing because I have heard AIX is a mixing of Unix and IBM mainframe
> code.
>
> I have attached a clean version of the code because the web mail archive
> munged the C code. I called it tst1.c. If you compile it and run it
> like this:
>
> #$ time tst1 1
>
> real 0m10.013s
> user 0m0.000s
> sys 0m0.004s
>
> This runs select(1) 1000 times, meaning 10ms per select for BSD/OS.

Bingo. It seems AIX 5L can run select() at 1ms timing.

bash-2.04$ time ./a.out 1

real 0m1.027s
user 0m0.000s
sys 0m0.000s
--
Tatsuo Ishii