Changes between Version 1 and Version 2 of CombiningOperations

Timestamp:

10/27/09 14:35:30 (4 weeks ago)

Author:

robl (IP: 205.208.56.252)

Comment:

--

CombiningOperations

@@ -1 @@
-This text is taken mostly from the abstract of Kui's
-[http://www.mcs.anl.gov/events/workshops/iasds09/ IASDS]
-paper (Kui Gao,
-Wei-keng Liao, Alok Choudhary, Robert Ross, and Robert Latham. "Combining I/O
-Operations for Multiple Array Variables in Parallel NetCDF". In the ''Proceedings
-of  the Workshop on Interfaces and Architectures for Scientific Data Storage'',
-held in conjunction with the the IEEE Cluster Conference, New Orleans,
-Louisiana, September 2009. )
-
-{{{
+== Motivation == 
 Array variables comprise the bulk of the data in a netCDF dataset, and for
 accesses to large regions of single array variables, PnetCDF attains very high
@@ -17 +8 @@
 much higher performance with larger request sizes. Moreover, the record
 variables data is stored interleaved by record, and the contiguity information
-is lost, so the existing MPI-IO collective I/O optimization can not help. This
-paper presents a new mechanism for PnetCDF to combine multiple I/O operations
+is lost, so the existing MPI-IO collective I/O optimization can not help.
+
+We provided a new mechanism for PnetCDF to combine multiple I/O operations
 for better I/O performance.  This mechanism can be used in a new function that
 takes arguments for reading/writing multiple array variables, allowing
@@ -26 +18 @@
 to the application. Our performance results demonstrate significant
 improvement using well-known application benchmarks.
-}}}
+
+== Usage == 
 
 There are two ways to use this feature:
 
-'''Implicit Method:''' New routines (e.g. ncmpi_mput_vara_all) take a list of variables to access
+'''Explicit Method:''' New routines (e.g. ncmpi_mput_vara_all) take a list of variables to access
 
-'''Explicit Method'''  Several variable accesses can be "scheduled" with the nonblocking routines (e.g. ncmpi_iput_vara_all).  Then, when the application waits for completion of those accesses, the library will service them all in a single call.
+'''Implicit Method'''  Several variable accesses can be "scheduled" with the
+nonblocking routines.   Then, when the application waits for completion of
+those accesses, the library will service them all in a single call.
 
+The function calls for the explicit method look like this:
+
+{{{
+int ncmpi_put_mvara_all(int ncid, int nvars, int varid[],
+                   MPI_Offset *start[], MPI_Offset *count[],
+                   void **buf, MPI_Offset *bufcount,
+                   MPI_Datatype *datatype);
+
+int ncmpi_get_mvara_all(int ncid, int nvars, int varid[],
+                   MPI_Offset *start[], MPI_Offset *count[],
+                   void **buf, MPI_Offset *bufcount,
+                   MPI_Datatype *datatype);
+}}}
+
+== References ==
+Kui Gao,
+Wei-keng Liao, Alok Choudhary, Robert Ross, and Robert Latham. "Combining I/O
+Operations for Multiple Array Variables in Parallel NetCDF". In the ''Proceedings
+of  the [http://www.mcs.anl.gov/events/workshops/iasds09 Workshop on Interfaces and Architectures for Scientific Data Storage]'',
+held in conjunction with the the IEEE Cluster Conference, New Orleans,
+Louisiana, September 2009.  PDF HERE
+