[mpich2-dev] [mpi-all-commits] r3669 - mpich2/branches/dev/knem/src/mpid/ch3/channels/nemesis/nemesis/src

[William Gropp]

This change reminded me that there are standards in MPICH for  
parameter handling to provide some uniformity and (in the full case)  
embedded self documentation.  Its very easy for a large package like  
MPICH2 to accumulate a wide variety of parameters with different  
handling and naming conventions, and it is easier on everyone in the  
long run if these follow a standard form.

In brief, the standard suggests using MPICH_ as the prefix and using a  
common set of routines that can ensure that the values are available  
and correct (what happens if I set this value to the string "64k").

Bill

On Dec 9, 2008, at 6:36 PM, bgoglin at mcs.anl.gov wrote:

> Author: bgoglin
> Date: 2008-12-09 18:36:48 -0600 (Tue, 09 Dec 2008)
> New Revision: 3669
>
> Modified:
>   mpich2/branches/dev/knem/src/mpid/ch3/channels/nemesis/nemesis/src/ 
> mpid_nem_lmt_dma.c
> Log:
> set NEM_LMT_DMA_THRESHOLD=<n> in the environment to change the DMA  
> threshold, 2MB by default
>
> Modified: mpich2/branches/dev/knem/src/mpid/ch3/channels/nemesis/ 
> nemesis/src/mpid_nem_lmt_dma.c
> ===================================================================
> --- mpich2/branches/dev/knem/src/mpid/ch3/channels/nemesis/nemesis/ 
> src/mpid_nem_lmt_dma.c	2008-12-09 22:16:00 UTC (rev 3668)
> +++ mpich2/branches/dev/knem/src/mpid/ch3/channels/nemesis/nemesis/ 
> src/mpid_nem_lmt_dma.c	2008-12-10 00:36:48 UTC (rev 3669)
> @@ -50,7 +50,12 @@
>     int err;
>     int i;
>     struct knem_cmd_info info;
> +    char *env;
>
> +    env = getenv("NEM_LMT_DMA_THRESHOLD");
> +    if (env)
> +      dma_threshold = atol(env);
> +
>     knem_fd = open(KNEM_DEVICE_FILENAME, O_RDWR);
>     MPIU_ERR_CHKANDJUMP2(knem_fd < 0, mpi_errno, MPI_ERR_OTHER,  
> "**shm_open",
>                          "**shm_open %s %d", KNEM_DEVICE_FILENAME,  
> errno);
>

William Gropp
Deputy Director for Research
Institute for Advanced Computing Applications and Technologies
Paul and Cynthia Saylor Professor of Computer Science
University of Illinois Urbana-Champaign