Re: [HACKERS] Re: v7.1b4 bad performance

* Tom Lane <tgl@sss.pgh.pa.us> [010216 22:49]:
> "Schmidt, Peter" <peter.schmidt@prismedia.com> writes:
> > So, is it OK to use commit_delay=0?
>
> Certainly.  In fact, I think that's about to become the default ;-)
>
> I have now experimented with several different platforms --- HPUX,
> FreeBSD, and two considerably different strains of Linux --- and I find
> that the minimum delay supported by select(2) is 10 or more milliseconds
> on all of them, as much as 20 msec on some popular platforms.  Try it
> yourself (my test program is attached).
>
> Thus, our past arguments about whether a few microseconds of delay
> before commit are a good idea seem moot; we do not have any portable way
> of implementing that, and a ten millisecond delay for commit is clearly
> Not Good.
>
>             regards, tom lane
Here is another one.  UnixWare 7.1.1 on a P-III 500 256 Meg Ram:

$ cc -o tgl.test -O tgl.test.c
$ time ./tgl.test 0

real    0m0.01s
user    0m0.01s
sys     0m0.00s
$ time ./tgl.test 1

real    0m10.01s
user    0m0.00s
sys     0m0.01s
$ time ./tgl.test 2

real    0m10.01s
user    0m0.00s
sys     0m0.00s
$ time ./tgl.test 3

real    0m10.11s
user    0m0.00s
sys     0m0.01s
$ uname -a
UnixWare lerami 5 7.1.1 i386 x86at SCO UNIX_SVR5
$

--
Larry Rosenman                     http://www.lerctr.org/~ler
Phone: +1 972-414-9812                 E-Mail: ler@lerctr.org
US Mail: 1905 Steamboat Springs Drive, Garland, TX 75044-6749