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

Tom Lane wrote:
> 
> > platform) i686-pc-linux-gnu, compiled by GCC egcs-2.91.60(turbolinux 4.2)
> > min delay) 10msec according to your test program.
> > -B)  64 (all other settings are default)
> 
> Thanks.  Could I trouble you to run it again with a larger -B, say
> 1024 or 2048?  What I've found is that at -B 64, the benchmark is
> so constrained by limited buffer space that it doesn't reflect
> performance at a more realistic production setting.
> 

Hmm the result doesn't seem that obvious.

First I got the following result.
[CommitDelay=0]
1)tps = 23.024648(including connections establishing)
  tps = 23.856420(excluding connections establishing)
2)tps = 30.276270(including connections establishing)
  tps = 30.996459(excluding connections establishing)
[CommitDelay=1]
1)tps = 23.065921(including connections establishing)
  tps = 23.866029(excluding connections establishing)
2)tps = 34.024632(including connections establishing)
  tps = 35.671566(excluding connections establishing)

The result seems inconstant and after disabling 
checkpoint process I got the following.

[CommitDelay=0]
1)tps = 24.060970(including connections establishing)
  tps = 24.416851(excluding connections establishing)
2)tps = 21.361134(including connections establishing)
  tps = 21.605583(excluding connections establishing)
3)tps = 20.377635(including connections establishing)
  tps = 20.646523(excluding connections establishing)
[CommitDelay=1]
1)tps = 22.164379(including connections establishing)
  tps = 22.790772(excluding connections establishing)
2)tps = 22.719068(including connections establishing)
  tps = 23.040485(excluding connections establishing)
3)tps = 24.341675(including connections establishing)
  tps = 25.869479(excluding connections establishing)

Unfortunately I have no more time to check today.
Please check the similar test case.

[My test case]
I created and initialized 10 datatabases as follows.
1) create databases.
   createdb inoue1
   craetedb inoue2
   .
   createdb inoue10
2) pgbench -i inoue1
   pgbench -i inoue2
   .
   pgbench -i inoue10
3) invoke a modified pgbench
   pgbench -c 10 -t 100 inoue

I've attached a patch to change pgbench so that
each connection connects to different database
whose name is 'xxxx%d'(xxxx is the specified
database? name).

Regards,
Hiroshi Inoue