[AGENT++] SNMP v3 get performance

[Frank Fock]

Hi John,

You can discovered the engine ID by sending a single
SNMPv3 PDU. I think SNMP++ already provides such a
function.

Frank

John McCaskey wrote:
> Hi Frank,
> 
> Thanks for the response.  The only issue I see with your approach is 
> that I don't know the remote agents engine IDs.  If I try to go with 
> that approach is there a good efficient way to discover the engine IDs 
> as well, or will I need to gather and know them upfront if I'm to 
> achieve good performance?
> 
> John
> 
> On 3/20/06, *Frank Fock* <fock at agentpp.com <mailto:fock at agentpp.com>> wrote:
> 
>     Hi John,
> 
>     I think adding localized users only will provide
>     best performance. As you know the user/passphrase
>     combination for all agents, you can localize them
>     with the agent's engine IDs and add them all to
>     the USM before you start polling. After that, you
>     do not need to modify the USM anymore.
> 
>     Best regards,
>     Frank
> 
>     John McCaskey wrote:
>      > Everyone,
>      >
>      > Using the patch I previously provided for per session v3MP
>     objects I have my
>      > polling engine running and stable using SNMP++ for all of our SNMP
>      > requests.  I have 80 threads that get spawned, each create's it's
>     own v3MP
>      > object, and each checks a global queue for devices that need SNMP
>     polling.
>      > Each thread then once it has a device sets up a new snmp session,
>     which
>      > includes doing a usm->add_usm_user() call if the device is using
>     v3, and
>      > then issues SNMP get requests on groups of OIDs until it has
>     gathered all
>      > the data needed for the device.
>      >
>      > This works well, but the performance when polling a large number
>     of v3
>      > devices is pretty bad.  For v1 I can poll several thousand
>     devices in a
>      > matter of a minute or two and performance is quite good on par
>     with Net-SNMP
>      > which we used previously.  However, if I have just a couple
>     hundred v3
>      > devices the performance starts to crawl.  Under my linux build
>     I've been
>      > using oprofile to gather some performance data and it seems that
>     the bulk of
>      > the time is being spent in the MD5 routines, I'm testing with a
>     security
>      > level of authPriv using MD5/DES.  Here is the output from oprofile:
>      >
>      > CPU: P4 / Xeon with 2 hyper-threads, speed 2592.35 MHz (estimated)
>      > Counted GLOBAL_POWER_EVENTS events (time during which processor
>     is not
>      > stopped) with a unit mask of 0x01 (mandatory) count 100000
>      > samples % linenr info symbol name
>      > 9306146 64.4420 md5c.cpp:220 MD5Transform
>      > 3414196 23.6422 auth_priv.cpp:1040
>     AuthMD5::password_to_key(unsigned char
>      > const*, unsigned int, unsigned char const*, un
>      > signed int, unsigned char*, unsigned int*)
>      > 821898 5.6914 md5c.cpp:332 Decode
>      >
>      > I'm interested in any suggestions on cutting down this time.  I
>     know Jochen
>      > already mentioned that I shouldn't keep calling add_usm_user if
>     the user has
>      > already been added previously, but given that each device may
>     have any
>      > user/password combination and I have no way of knowing whether a
>     device may
>      > use the same username as another, but have a different password I
>     don't see
>      > how I can avoid that.  It seems like maybe what I need is for the
>     table of
>      > added users inside snmp++ to be a little smarter and not lookup
>     by just
>      > username but also by password so that whenever I add it will
>     reuse if an
>      > exact match exists otherwise add the user again and perform the MD5
>      > computations again.  Does that seem like the best approach to
>     improving
>      > performance?
>      >
>      > John McCaskey
>      > Klir Technologies, Inc.
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> 
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