Charles,
On 21.07.08, Charles Bacon wrote:
> Interesting - I remember some discussion like that on this list, I
> think, but what does that rule achieve?
>
This is part of the AstroGrid-D documentation (I think I added it)
http://www.gac-grid.org/project-products/grid-support/grid-installation.html#gsiftp
As to where it came from, I haven't yet heard from Thomas, but I found
a discussion in which he took part (in German) on the internal GACG WG1
mailing list, dated 3 Sep. 2007
Thomas says there, that he was able to watch the TCP traffic during some
grid exchanges, and that (in particular) GridFTP tries to connect with an
'identd' server, which in case of a firewall, results in a dropped packet
and usually a 30-second timeout.
He then goes on to say that he thinks he saw the iptables rule in a firewall
document, probably on the Globus website. I haven't located that document.
Anyway, the iptables rule solved Art's problem, as well as ours.
Cheers!
> On Jul 21, 2008, at 4:39 AM, Steve White wrote:
>
> >Art,
> >
> >As I understand it, your application runs a single process in the
> >"fork"
> >job manager. So you are referring to the latency in running a single
> >simple process, rather than to that in submission to a batch system.
> >
> >I now remember that last September, Thomas Brüsemeister pointed out to
> >us a work-around for a similar problem, at least regarding file
> >transfers.
> >It was to add the following 'iptables' rule:
> >
> >iptables -A OUTPUT -p tcp --syn --dport 113 -j REJECT --reject-with
> >tcp-reset
> >
> >We implemented this on many of our systems at AIP, and observed a big
> >improvement in some kinds of latencey. Now I see that on some of them
> >the setting has been lost (after system upgrades, etc.)
> >
> >Would this improve things for your application?
> >
> >Cheers!
> >
> >
> >On 20.07.08, Arthur Carlson wrote:
> >>In the thread "Globus not for real-time application?", a number of
> >>users
> >>discuss whether it is realistic or not to get latencies below 1
> >>second.
> >>Sounds like paradise. I am seeing latencies of up to a minute!
> >>
> >>My workstation, gavosrv1.mpe.mpg.de, not the newest anymore, has GTK
> >>4.0.5 installed. When I use globusrun-ws to go from this machine
> >>back to
> >>itself, ... but just look:
> >>
> >> [EMAIL PROTECTED] ~]$ time globusrun-ws -submit -s -F gavosrv1 -c /
> >>bin/true
> >> Delegating user credentials...Done.
> >> Submitting job...Done.
> >> Job ID: uuid:52f0f962-54e1-11dd-a56f-0007e914d571
> >> Termination time: 07/19/2008 15:51 GMT
> >> Current job state: Active
> >> Current job state: CleanUp-Hold
> >> Current job state: CleanUp
> >> Current job state: Done
> >> Destroying job...Done.
> >> Cleaning up any delegated credentials...Done.
> >>
> >> real 0m24.327s
> >> user 0m1.242s
> >> sys 0m0.113s
> >>
> >>Note that "user" and "sys" times are reasonable. Almost all of this
> >>time
> >>passes between "CleanUp" and "Done". It can't just be checking
> >>credentials because gsissh is done in a jiffy:
> >>
> >> [EMAIL PROTECTED] ~]$ time gsissh -p 2222 gavosrv1
> >> /bin/true
> >>
> >> real 0m0.649s
> >> user 0m0.134s
> >> sys 0m0.020s
> >>
> >>Maybe that is already enough for someone to see where the problem
> >>lies.
> >>I can also point out that all (at least many) of the machines in our
> >>grid (AstroGrid-D) seem to be affected, but to varying degrees.
> >>Here is
> >>a little matrix of tests:
> >>
> >>from gavosrv1.mpe.mpg.de to gavosrv1.mpe.mpg.de: 0m27.235s
> >>from gavosrv1.mpe.mpg.de to titan.ari.uni-heidelberg.de: 0m14.324s
> >>from gavosrv1.mpe.mpg.de to udo-gt03.grid.tu-dortmund.de: 0m8.823s
> >>
> >>from titan to gavosrv1.mpe.mpg.de: 0m57.208s
> >>from titan to titan.ari.uni-heidelberg.de: 0m16.875s
> >>from titan to udo-gt03.grid.tu-dortmund.de: 0m27.225s
> >>
> >>from udo-gt03 to gavosrv1.mpe.mpg.de: 1m5.221s
> >>from udo-gt03 to titan.ari.uni-heidelberg.de: 0m12.905s
> >>from udo-gt03 to udo-gt03.grid.tu-dortmund.de: 0m6.952s
> >>
> >>Please tell me I am doing something really stupid. For production
> >>of my
> >>application even a minute of latency is not a big deal, but it's a
> >>pain
> >>during development and debugging. Right now I am using gsissh
> >>instead of
> >>globusrun-ws just to work around this.
> >>
> >>Thank for the lift,
> >>Art Carlson
> >>AstroGrid-D Project
> >>Max-Planck-Institute für extraterrestrische Physik, Garching, Germany
> >>
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