Re:

On Tue, 15 Feb 2005, Magnus Hagander wrote:

> Run:
> hdparm -I /dev/hda
>
> If you get a line like:
> Commands/features:
>        Enabled Supported:
>           *    READ BUFFER cmd
>           *    WRITE BUFFER cmd
>           *    Host Protected Area feature set
>           *    Look-ahead
>           *    Write cache
> ...
> (last line is what matters here)
> you have write cacheing enabled.

Thanks. Ok, really I have it enabled (fortunately :)

>
> To turn it of, run
> hdparm -W0 /dev/hda

Done. Now it is disabled.

>
> Not sure if you need to reboot, I don'tt hink so. Then re-run the
> benchmark on linux.

No, under Linux reboot makes nothing (it is completely dynamical system).

Now I have

/usr/local/pgsql/bin:14>pgbench -c 1 -t 500
starting vacuum...end.
transaction type: TPC-B (sort of)
scaling factor: 1
number of clients: 1
number of transactions per client: 500
number of transactions actually processed: 500/500
tps = 89.528064 (including connections establishing)
tps = 89.560730 (excluding connections establishing)


It is about 9 times slower. But again 4 times faster then under Windows.

After

root@390x:/e# hdparm -W1 /dev/hda

/dev/hda: setting drive write-caching to 1 (on)


/usr/local/pgsql/bin:24>pgbench -c 1 -t 500
starting vacuum...end.
transaction type: TPC-B (sort of)
scaling factor: 1
number of clients: 1
number of transactions per client: 500
number of transactions actually processed: 500/500
tps = 846.189777 (including connections establishing)
tps = 849.481986 (excluding connections establishing)


Regards,
E.R.
_________________________________________________________________________
Evgeny Rodichev                          Sternberg Astronomical Institute
email: er@sai.msu.su                              Moscow State University
Phone: 007 (095) 939 2383
Fax:   007 (095) 932 8841                       http://www.sai.msu.su/~er