Gurus needed to diagnose severe performance degradation Post: 302350019

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Top Forums UNIX for Advanced & Expert Users Gurus needed to diagnose severe performance degradation Post 302350019 by Neo on Wednesday 2nd of September 2009 02:14:27 PM

09-02-2009

Administrator

Quote:

Originally Posted by Corona688

How close can it get? I regularly get 90MB with 100baseT, but haven't seen higher than 300MB on our gigabit lines.

Well, it has been a long time since I had to do these calculations. The limits are published by IEEE (assuming point-to-point in this discussion) - I would have to Google for the numbers.

---------- Post updated at 18:14 ---------- Previous update was at 18:03 ----------

Also, I forgot to mention that the theoretical maximum for point-to-point Ethernet (assuming no other network devices talking on the channel), is different, of course, than the practical maximum based on things like "length of cable run", "crimps in the cable" , "connector losses", etc.

I once was on a site where the entire performance of the network management system was terrible and the problem was a crimped cable (I think someone rolled their chair across it in the data center, LOL)

That is why I advise to focus on the network channel(s) when you are debugging performance issues on distributed applications.

Neo

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lamnodes

LAMNODES(1)                                                          LAM TOOLS                                                         LAMNODES(1)

NAME

       lamnodes - Resolve LAM node/CPU notation to Unix hostnames.

SYNOPSIS

       lamnodes [-chin] [where]

OPTIONS

       -c          Suppress printing the CPU count for each node.

       -h          Print the command help menu.

       -i          Print IP addresses (instead of IP names)

       -n          Suppress printing CPU count for each node

DESCRIPTION

       The  lamnodes command is used to resolve LAM node/CPU nomenclature to Unix hostnames.  It can be used to determine the current running con-
       figuration of the LAM/MPI run-time environment, and generate a boot schema that can be used to launch LAM in the future.

       By default, lamnodes will print out the node number, default IP name, CPU count, and per-node flags for  each  node  in  the  running  LAM.
       gethostbyaddr(3) is used to obtain default hostnames.  If gethostbyaddr(3) fails, the IP number is displayed instead.

       This  command  can be used by setup shell scripts (and the like) to determine information from a currently-running LAM universe.  For exam-
       ple, use lamnodes to resolve particular CPUs and/or nodes to specific unix hostnames.  In a batch environment,  lamnodes  can  be  used  to
       determine which CPUs share a common node (note that MPI_GET_PROCESSOR_NAME can be used for a similar effect in an MPI program).

       lamnodes also shows per-node flags.  Currently defined flags are:

       origin      The node where lamboot was executed.

       this_node   The node where lamnodes is running.

       no_schedule The node will not be used to run MPI and serial processes when N and C are used to mpirun and lamexec.

EXAMPLES

       lamnodes N -n
           Display IP names and CPU counts for all nodes.  This output can be saved and later used with lamboot(1).

       lamnodes C -n -c
           Display  the  IP  name  of the nodes containing each CPU, and suppress the LAM node number and CPU count.  This output can be saved and
           later used with lamboot(1).

SEE ALSO

       bhost(5), gethostbyaddr(3), lamboot(1)

LAM 7.1.4                                                           July, 2007                                                         LAMNODES(1)