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