Re: sanity check on updating from HDB backend to MDB

[Christopher Wood <christopher_wood@pobox.com>]

On Tue, Aug 12, 2014 at 03:22:57PM -0400, Brian Reichert wrote:
> On Tue, Aug 12, 2014 at 02:04:20PM -0400, Brian Reichert wrote:
> > On Tue, Aug 12, 2014 at 11:12:51AM -0700, Howard Chu wrote:
> > > While that search is running you should see slapd at 100% CPU. If not, then 
> > > something in your system is throttling your connection.
> > 
> > And it is not at 100%.  'top' shows slapd on this host is only at ~50%.
> > 
> > I'll review the 'threads' setting.
> 
> Progress!
> 
> The 'ldap' user has no system limits set on it:
> 
>   # setuidgid ldap sh -c ulimit -a
>   unlimited
> 
> I have 2 CPUs with 4 cores each:
> 
>   # grep "^physical id" /proc/cpuinfo | sort -u | wc -l
>   2
>   # grep "^cpu cores" /proc/cpuinfo | sort -u
>   cpu cores       : 4
> 
> This page recommends:
> 
>   http://www.openldap.org/doc/admin24/tuning.html#{{slapd}}%288%29%20Threads
> 
>   This value should generally be a function of the number of "real"
>   cores on the system, for example on a server with 2 CPUs with one
>   core each, set this to 8, or 4 threads per real core.
> 
> Assuming 'real core' == CPU, in my case, I think this should be 8
> (4 * 2 physical CPUs).  Is that correct?
> 
> It was set to 32 (I have no idea why), and 'top' showed ~50%.
> 
> When I changed threads to '8', my query times dropped to ~22 seconds,
> which is _much_ better than the 175 I was seeing.
> 
> 'top' still shows slapd only using %50, so I hazard that it keeps
> to one CPU.  Is that a valid assumption?

Try pressing "1" to have top show individual CPUs.

> Could this mdb database perform better?  It's outperforming my bdb
> backend by %25, which isn't too shabby, but I'm curious if this
> sort of performance increase is typical...
> 
> -- 
> Brian Reichert				<reichert@numachi.com>
> BSD admin/developer at large	
>