[Omp] Working with threadprivate elements of structs

[Shah, Sanjiv]

Clay,
 
Addresses of threadprivate objects are not constant, so as soon as you
make static_ltree threadprivate, you will not be able to use it in the
structure initialization for l_desc.  You will have to initialize the
tree field with NULL and then use a dummy parallel region, as you
suggest, to set up the correct linkages.  The code should be just a
simple assignment in the parallel region.
 
Sanjiv
 

-- 
Sanjiv, 217-403-4244 

 

  _____  

From: Omp-bounces at openmp.org [mailto:Omp-bounces at openmp.org] On Behalf
Of Breshears, Clay
Sent: Friday, January 09, 2004 5:45 PM
To: omp at openmp.org
Subject: [Omp] Working with threadprivate elements of structs




I need to have a threadprivate array that is pointed to by a
threadprivate struct.  How do I declare and initialize these so they all
refer to the correct versions?

In a C code, I have an array that needs to be threadprivate.  The
original serial code also includes a struct (used as a descriptor to
carry additional information about the array and its contents) that is
also used as a parameter to some function calls.  The fields of the
descriptor instances are statically initialized at declaration time.
For example, the serial code looks something like:

ct_data static_ltree[100]; 

typedef struct tree_desc { 
   ct_data *tree; 
   int max_length; 
   int max_code; 
} tree_desc; 

tree_desc l_desc = {static_ltree, MAX_LEN, 0}; 

If I put in pragmas to set static_ltree and l_desc to be threadprivate,
how can I guarantee that each thread's copy of static_ltree will be
pointed to by that same thread's copy of l_desc?  Do I need to use a
"dummy" parallel region to access static_ltree and initialize l_desc in
parallel to make sure the desired linkage occurs?  Does the static
initialization of l_desc suffice to hook things up correctly?  Is there
a better or simpler way?

Thanks in advance for any help or advice. 

                                                clay 
-- 
Clay Breshears   
Parallel Applications Engineer 
KAI Software Labs, a division of Intel Americas, Inc.   
phone: 217-403-4206  fax: 217-403-4399 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.openmp.org/pipermail/omp/attachments/20040109/630f971b/attachment.html