Tom Lane wrote:

>Attached is a modification that prevents additional waiters from being
>released until the first releasee has a chance to run and acquire the
>lock.  Would you try this and see if it's better or not in your test
>cases?  It doesn't seem to help on a single CPU, but maybe on multiple
>CPUs it'll make a difference.
>
Here are some results for Linux 2.2 on a Dual PentiumPro 200MHz, SCSI 
disks and way too litte RAM
(just 128MB). I observed the loadavg. with the three different 7.2 
versions and 50 clients, without patch
the load stayed low (2-3), with patch no1 very high (12-14) and with 
patch no2 between the two others
(6-8). Any of the patches seem to be a big win with the second version 
being slightly better. I could run
benchmarks on 7.1 if that would be interesting. I used the same 
benchmark database with a
VACUUM FULL between each version of the backend tested. I also re-run 
some of the tests on the same
database after I tested all loads on the different versions, and numbers 
stayed very simmilar (difference:
 0.1-0.3 tps).

Best regrds
    Fredrik Estreen

In response to

• Re: LWLock contention: I think I understand the problem at 2001-12-30 18:04:29 from Tom Lane

Responses

• Re: LWLock contention: I think I understand the problem at 2002-01-04 01:02:54 from Tom Lane
• Transaction tests on SMP Linux at 2002-01-04 02:35:11 from Kenny H Klatt

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