[Freeipa-devel] slow response

[Simo Sorce]

On Tue, 2012-07-31 at 08:49 -0700, Stephen Ingram wrote:
> On Tue, Jul 31, 2012 at 1:39 AM, Petr Spacek <pspacek at redhat.com> wrote:
> > On 07/31/2012 12:27 AM, John Dennis wrote:
> >>
> >>
> >> What is taking so long with session bookkeeping? I don't know yet. I would
> >> need more timing instrumentation. I will say when I looked at the
> >> python-krb5
> >> code (which we use to populate the ccache from the session and read back
> >> to
> >> store in the session) seemed to be remarkably inefficient. We also elected
> >> to
> >> use file based ccache rather than in-memory ccache (that means there is a
> >> bit
> >> of file-IO occurring).
> >
> >
> > A note regarding python-krbV:
> > I used python-krbV extensively in my thesis for KDC stress test. Python-krbV
> > can obtain several thousands of TGTs per second (even with ccache in a
> > file). AFAIK VFS calls are not done synchronously. But others parts of
> > python-krbV were left uncovered, so it can contain some surprises.
> >
> > === Wild speculation follows ===
> > 1.5 second is incredibly long time, it sounds like some kind of timeout.
> > Krb5 libs have usual timeout = 1 second per request.
> >
> > Are all KDCs in /etc/krb5.conf alive and reachable?
> 
> In this case, as I'm referring to the extreme slowness of the Web UI,
> the KDC is on the same system (the ipa server) that is making the
> request, correct?
> 
> > Is SSSD running on problematic server?
> 
> Yes. Again, I'm guessing the problematic server is the IPA server itself.
> 
> > Is proper KDC selected by SSSD KDC auto-locator plugin?
> > (See /var/lib/sss/pubconf/)
> 
> Yes, I checked that file and it is the IP address of the IPA server on
> the same server. Perhaps should this be 127.0.0.1 instead?
> 
> I also have checked the resolv.conf file, and indeed the IP points to
> the IPA server itself (same machine) as expected. Both forward and
> reverse DNS work. I'm not really sure what else could be setup
> incorrectly to cause any KDC slowness.
> 
> Due to the extreme UI slowness issue, I have not created any replicas
> so this system is it. I'm not so sure I would be able to see the 1.5 s
> delay if it weren't compounded by the overall slowness of the Web UI,
> however, the KDC seems to perform well for other systems in the realm.
> I'm certainly not taxing it with a huge load, but tickets seem to be
> issued without delay.

Stephen,
another user sent me a wireshark trace for a similar performance issue.
So far I see a pause when doing the first leg of a SASL authentication.
This may well explain also your issue.

Can you test connecting to the ldap server using ldapsearch -Y GSSAPI
(you need a kerberos ticket) and telling me if you experience any
delay ?
If you could run a bunch of searches in a loop and take a wireshark
trace that may help analyzing the timings and seeing if there is a
correlation.

Simo.

-- 
Simo Sorce * Red Hat, Inc * New York