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Re: Log level and performances
Most syslog implementations allow logfiles to be written eighter in sync
or async mode. What does your's do?
Daniel van Eeden <email@example.com>
On Fri, 2004-04-16 at 10:52, BAILLEUX Benoît FTRD/DMI/CAE wrote:
> Two questiosn about OL performances when logging is activated.
> Someone asks me recently if logging has a high effect on OpenLDAP performances. As I have no information to answer him, I play with an OL instance already up, and I have a strange result.
> The platform :
> Dual processor PC, with Linux MDK 9.1, two HDD, 384 Mo RAM
> OpenLDAP 2.1.5, BDB 4.2.50 (data files and log file on separate disks)
> Directory loaded with two millions tiny entries, based on a very specific schema.
> Excerpt of the slapd.conf file :
> # -----------
> allow bind_v2
> threads 4
> reverse-lookup off
> loglevel <various - see below>
> database bdb
> suffix ...
> rootdn ...
> rootpw ...
> cachesize 500000
> idlcachesize 20000
> searchstack 8
> # -----------
> I use DirectoryMark (DM) to play just the same scenarios three times : one time with no log at all, one time with logelevel=256 (directed to syslog) and one time with loglevel=0 but the "-d 256" option on command line, with redirection to a file.
> The DM scenario is very simple : 95% exact search, 5% modify. 5 client process with 2 threads. Measures are made after a warming up.
> The results are (tests repeated 3 times) :
> - no log : 2540 op/s (cool !)
> - loglevel=256 : 29 op/s (uh !)
> - slapd -d 256 : 2577 op/s
> So I have two questions :
> - is there a problem with my configuration that makes slapd so slow when it logs to syslog ?
> - why is the throughput slightly better (and not clearly worst) when OL logs to stdout ?