Newsgroups: comp.parallel.pvm
From: jim@cicely.ilo.dec.com (Jim Lawton)
Reply-To: jim@ilo.dec.com
Subject: Re: Out of buffer error.
Organization: Digital Equipment Corporation
Date: 15 Aug 1995 13:43:44 GMT
Message-ID: <40q8ag$omr@mrnews.mro.dec.com>


In article <40o3l8$da5@catfish.cs.umd.edu>, ranga@cs.umd.edu (M.Ranganathan) writes:
>I am trying to debug an application using pvm on a network of alphas.
>I am using the ALPHAMP version of pvm 3.3.8.
>The app runs fine for a few thousand iterations and then I get
>
>libpvm [t40004]: da_new() Warning: shared buffer full, using malloc
>
>where is this coming from ?

Check out ~/pvm3/Readme.mp - it has some pertinent information 
regarding running PVM on shared-memory SMP machines (like ALPHAMP).

Basically:

 - you need to make sure that the PVM buffer is big enough to 
   handle the largest message (done either by setting the PVMBUFSIZE
   environment variable or the SHMBUFSIZE compile-time variable (in 
   pvm3/src/pvmshmem.h) to something larger than the default 1MB.

 - you may need to rebuild your kernel to increase the size of the
   largest shared-memory segment allowed (4MB default in Digital Unix).
   You can do "/sbin/sysconfig -q ipc" to check the size of the 
   various relevant kernel parameters ("shm-max" is the appropriate
   one in this case) and reconfigre/rebuild if necessary.

 - shared-memory PVM passes pointers to messages instead of packets;
   the actual data buffers are not freed up by pvm_recv; thus after 
   each pvm_recv you need to add a call to pvm_freebuf(). Also, if
   you save buffers (e.g. with pvm_setsbuf()) then you must also free 
   that buffer before calling pvm_exit() or the program will hang.

Hope this helps,

/jim

+---------------------------------------------------------------+
| Jim Lawton                      Digital Equipment Corporation | 
|                    Technical Computing Group, Galway, Ireland |
| Phone: +353-91-754759                     Fax: +353-91-754435 | 
| Email: jim@ilo.dec.com (MIME OK) Not an offical spokesperson! |
+---------------------------------------------------------------+

