Re: [Dpcl-develop] runtime AIS_SHM_SIZE

[Dave W. <dwo...@us...>]

Steve
There is no requirement that AIS_SHM_SIZE be a constant or that it be 
limited to 32MB. I picked this because this was the default  value on the 
i386 systems we had at the time.

If you have a way to determine a value at run time, there shouldn't be  a 
problem with the concept of dynamically determining the value. This has to 
be a Linux-specific change though, since we do have a 256MB shared memory 
limit in AIX. I'm not exactly sure of the semantics of 
/proc/sys/kernel/shmmax. If this is a per-request maximum, then using 
whatever it is set to is probably not a problem. If it nrepresents the 
maximum shared memory allocation for the entire system then you need to be 
careful that DPCL does not consume the entire allocation.

Dave



Steve Collins <sl...@sg...> 
Sent by: dpc...@li...
02/23/2005 01:28 PM

To
dpc...@li...
cc

Subject
[Dpcl-develop] runtime AIS_SHM_SIZE







    Hello everyone -

         I'm trying out the new mailing list to see if I'll get
      it right. 
         As part of the Open/SpeedShop Project at SGI, one of our
      government parters (MartinS at LLNL) has pointed out that the
      value of AIS_SHM_SIZE really needs to be computed at runtime to
      be accurate. Martin suggests querying the system via /proc and
      a sysctrl call. I think Martin is dead-on, but I have no feel
      for the code change that might be best. The current non-AIX
      value of 0x01000000 seems small for an ia64 architecture.
         Comments anyone?

                                             SteveC -

                                             SGI Compilers/Tools


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