New performance numbers

[Howard Chu <hyc@symas.com>]

Back in May 2006 we posted some authentication rate numbers for Symas CDS 
3.3.2 (based on OpenLDAP 2.3.21.) http://connexitor.com/blog/pivot/entry.php?id=49

On a 1 million entry database, we saw about 13K auths/second on a dual 
processor 2.8GHz Opteron system.

We've recently re-run the tests using OpenLDAP 2.4.5 on a dual processor 
2.8GHz dual-core Opteron system (so, 4 cores now instead of just 2) and gotten 
38K auths/second. One interesting thing to note is that we reached this same 
rate on back-bdb, with the slapd server at 100% CPU utilization, as well as 
with back-null, where slapd was only at 70% CPU. (This implies to me that 
there may have been a network bottleneck here, because we ought to have been 
able to drive slapd into 100% CPU usage even with back-null. Even gigabit 
ethernet has its limits...)

But the other nice point about this result is that while the number of CPU 
cores was increased by a factor of 2, the overall auth rates increased by a 
factor of 2.7. So we can see that OpenLDAP 2.4 is at least 35% faster than 
OpenLDAP 2.3. It also shows that the lightweight dispatcher is still scaling 
well with available CPU power.

Another point is the same thing I've harped on before - SLAMD is too 
inefficient on clients. We measured the 38K/sec rate using the slapd-auth C 
client that I just added to CVS HEAD. Using the SLAMD java client we could 
only reach 29K/sec, even with 12 client machines and 10 threads per client. 
Someone's going to have to sit down and write a C client that speaks the SLAMD 
server protocol and just fires off compiled C clients...
--
  -- Howard Chu
  Chief Architect, Symas Corp.  http://www.symas.com
  Director, Highland Sun        http://highlandsun.com/hyc/
  Chief Architect, OpenLDAP     http://www.openldap.org/project/