[Samba] Samba4 consumes more CPU

Prema premas at cdac.in
Mon Aug 26 11:09:31 MDT 2013

Dear Andrew,

As per your suggestion , I have attached the gdb log of the samba and smbd
process log running in the single server mode.
Also when I noted in the perf top, libndr.so consumes the maximum cpu.
I noticed that it happens soon after sometime the samba process is started
and the CPU is filled up.
Since the samba process occupies 100% atleast two or more CPUs out of 8 CPU
, the clients are not able to get authenticate to the server.
Kindly go through the logs and suggest what can be done to lessen the CPU

On Mon, Aug 12, 2013 at 11:45 AM, Andrew Bartlett <abartlet at samba.org>wrote:

> On Sun, 2013-08-11 at 10:12 +0530, Prema wrote:
> >
> > Also one more point  I would like to clarify., what is the maximum
> > User limit that Samba4 as a DC supports.
> >
> > I read somewhere that , there is a proportion between the system RAM +
> > hard disk size and user limit accepted in Samba4.
> >
> > Is that true., and in that case, how many users can be supported by a
> > 8 GB RAM and 500 GB hard disk size.
> >
> >
> > Kindly clarify this , since we have around 6k+ users spreaded for 20
> > DCs.
> G'Day,
> There are a few things going on here:
>  - The CPU utilisation isn't normal, for any use case.  If you were
> loading your system up to the maximum number of objects, for example, it
> would be slower, but as incoming authentication drop of, it would
> decrease back to normal levels.   To track down this, we need to work
> out what routine it consuing the CPU time, say with the linux 'perf'
> tools.  At the very least, attach to the process spinning with 'gdb -p
> <pid>' and get me the output of 'bt full', in the hope that this
> indicates the spinning routine.
>  - Samba does have limits in terms of the number of users it can
> currently efficiently serve, but that isn't at the 6000 user level, as
> far as we are aware
> Also you need to set your expectations regarding when I might be able to
> assist you:
>  - Please send all mail, unless confidential to the
> samba at lists.samba.org mailing list.  That way, others can help you.
> You may send it to me if you like, but ensure you always also send it to
> the list.  This also means that others can learn from any answers I
> give, rather than them staying private, and others can help you when I'm
> not available.
>  - While I work on Samba, and I'm very grateful to my employers for the
> time I'm able to spend on it, but you need to give us all a reasonable
> time to reply, understanding that we may not work the same hours and
> days that you do.  For example, I'll be on leave most of this coming
> week.
> Finally, a crash in Samba, and this is essentially what you describe, is
> serious, and I certainly understand your worry.
> Andrew Bartlett
> --
> Andrew Bartlett
> http://samba.org/~abartlet/
> Authentication Developer, Samba Team           http://samba.org
> Samba Developer, Catalyst IT                   http://catalyst.net.nz

Prema S

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