Re: Performance degredation between 2.4.39 and 2.4.44

[Quanah Gibson-Mount <quanah@zimbra.com>]

--On Tuesday, March 15, 2016 1:31 PM +0000 Howard Chu <hyc@symas.com> wrote:

> > I see the differences I've noted with at least 3 different DBs of
> > varying size now. I've dropped the 300kish one on ada.
>
> With your 300k entry DB and config I see a full subtree search take about
> 10.4s with rtxnsize = 0, vs 11.7s with rtxnsize = 10000. Measurable
> certainly, but not really noticeable.

As I noted, a 30:1 ratio seems to work ok.  Now, if you go back to my 
original mail, the problem is the default of 10k is clearly not sufficient 
for any medium+ sized db.  I think a mistake was made in setting the 
default in 2.4.44 to anything other than zero.  This is clearly an item 
that needs tuning PER database, and should not have a default that creates 
a severe performance penalty on databases > 300000 entries.  As you can see 
from my other emails, the further you get from the 30:1 ratio, the more 
significant the penalty in performance.  It would be interesting to know if 
there are further ways to optimize the code so that the penalty is not so 
severe.  I.e., the next step would be to set the rtxnsize to 1000 with the 
300k database and see if there are further optimizations to be had.

--Quanah

--

Quanah Gibson-Mount
Platform Architect
Zimbra, Inc.
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