Re: Performance issues lately.

[Howard Chu <hyc@symas.com>]

Jorgen Lundman wrote:
> No real reason, tried various different settings but to no real advantage.
>
> Now I have:
>
> Filesystem             size   used  avail capacity  Mounted on
> swap                    19G   7.7G    11G    42%    /tmp
>
> # grep cache DB_CONFIG
> set_cachesize 8 0 1
>
> # time /usr/local/BerkeleyDB.4.8/bin/db_stat -d id2entry.bdb
> real    6m6.099s
>
> # time cp id2entry.bdb /dev/null
> real    0m0.040s
> (It's not on disk)
>
> I thought to delete id2entry.bdb, and use slapindex to re-generate it but that
> appears not to be a supported feature. slapindex can not run without a valid
> id2entry.bdb. This is why I tried slapcat, rm *, slapadd. But no difference in
> speed up.
>
> If I truss with -u *:* (All inter-library calls) I get no "single" large system
> call, just a lot of work somewhere (that does not call read/write etc). Alas,
> the number of lines in truss file is:
>    6209933 /var/tmp/db_stat_truss

truss is pretty much useless in this context. Most of BDB's activity is thru 
memory-mapping, which involves no system calls for truss to trace. You need an 
actual profile (e.g. using oprofile) to identify where the time is going.

--
  -- Howard Chu
  CTO, Symas Corp.           http://www.symas.com
  Director, Highland Sun     http://highlandsun.com/hyc/
  Chief Architect, OpenLDAP  http://www.openldap.org/project/