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Re: Slapd running very slow



--On Tuesday, April 21, 2015 11:54 AM -0400 Brian Reichert <reichert@numachi.com> wrote:

On Tue, Apr 21, 2015 at 08:52:29PM +1000, Geoff Swan wrote:

I have an ldap server that appears to slow down significantly even under
moderate load, and wondered if there were any suggestions as to where to
look.

Using openldap-2.4.40 with mdb backend, on a dual Xeon (6 cores each)
server with 128GB ram.
Linux kernel 3.13, separate ext4 db volume (SAS). Slapd configured with
48 threads.

The problem appears that as soon as there are a handful of write
operations, slapd appears to stall. Binding to the ldap port takes many
seconds (instead of instant), and the slapd process appear to occupy
100% of a single CPU core.

What does your config file look like?

In particular, what does this setting look like for you:

  # Threads - four per CPU
  threads 8

According to his summary, he's using 48 threads. 4 per CPU/core was a good rule of thumb with bdb/hdb. So far in playing with back-mdb, it's seemed closer to 2 per CPU/core for me in benchmarking.

I'd generally advise testing current RE24 out, as there were some significant issues in 2.4.40 release.

--Quanah


--

Quanah Gibson-Mount
Platform Architect
Zimbra, Inc.
--------------------
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