PREMA SW4 - Revision history

Pthomadakis: /* SW4lite */

2020-01-27T19:23:58Z

‎SW4lite

Pthomadakis: /* SW4lite */

2020-01-27T17:31:38Z

‎SW4lite

Pthomadakis: /* SW4lite */

2020-01-27T17:29:26Z

‎SW4lite

Pthomadakis: /* SW4lite */

2020-01-27T17:29:09Z

‎SW4lite

Pthomadakis: /* SW4lite */

2020-01-27T17:28:38Z

‎SW4lite

Pthomadakis at 17:25, 27 January 2020

2020-01-27T17:25:19Z

Pthomadakis: /* Cluster: Wahab */

2020-01-23T22:24:11Z

‎Cluster: Wahab

Pthomadakis: /* PREMA Times */

2020-01-23T22:14:55Z

‎PREMA Times

Pthomadakis: /* Cluster: Wahab */

2020-01-23T22:14:20Z

‎Cluster: Wahab

Pthomadakis: /* Cluster: Turing */

2020-01-23T22:14:08Z

‎Cluster: Turing

@@ Line 18: / Line 18: @@
 * Each MPI rank holds partitions equal to the number of cores it utilizes.
 * Preprocessing computations are performed by invoking remote handlers on each of the partitions.
-* 2-sided communications are replaced with one-sided asynchronous remote method invocations.
+* Two-sided communications are replaced with one-sided asynchronous remote method invocations.
 The four-step communication pattern that takes place in the main iterative process of the application has been modified to ensure correctness.

@@ Line 1: / Line 1: @@
 == SW4lite ==
 [[File:SW4-Comm.png| thumb| 300px| right|Figure 1. The communication pattern of SW4lite proxy app.]]
-[[File:PREMA SW4.png| thumb| 450px| right|Figure 2. The modified communication pattern of SW4lite proxy app to work with PREMA .]]
+[[File:PREMA SW4.png| thumb| 400px| right|Figure 2. The modified communication pattern of SW4lite proxy app to work with PREMA. The blue arrows represent the data requests, while the red ones show the actual data transfers.]]
 In high-performance computing (HPC), proxy applications (“proxy apps”) are small, simplified codes that allow application developers to share important features of large applications without forcing collaborators to assimilate large and complex code bases. The Exascale Proxy Applications Project, part of the Exascale Computing Project (ECP), is a project where developers can share explore and share proxy apps.
@@ Line 25: / Line 25: @@
 To achieve this we have added two more steps to the communication pattern, one for each direction. The idea is that the communication in each direction begins with the receiver neighbor requesting
 the data to be sent to it when it's ready to receive them. The sender will send the data when it's ready to do so. In this way, we guarantee that both neighbors' data are consistent after the first step
-of communication in each direction. The requests for the second and fourth steps are implicit as they are received as part of the actual data sent in the first and third steps.
+of communication in each direction. The requests for the second and fourth steps are implicit as they are received as part of the actual data sent in the first and third steps. Figure 2 demonstrates the
 == MPI Times ==

@@ Line 1: / Line 1: @@
 == SW4lite ==
 [[File:SW4-Comm.png| thumb| 300px| right|Figure 1. The communication pattern of SW4lite proxy app.]]
-[[File:PREMA SW4.png| thumb| 350px| right|Figure 2. The modified communication pattern of SW4lite proxy app to work with PREMA .]]
+[[File:PREMA SW4.png| thumb| 450px| right|Figure 2. The modified communication pattern of SW4lite proxy app to work with PREMA .]]
 In high-performance computing (HPC), proxy applications (“proxy apps”) are small, simplified codes that allow application developers to share important features of large applications without forcing collaborators to assimilate large and complex code bases. The Exascale Proxy Applications Project, part of the Exascale Computing Project (ECP), is a project where developers can share explore and share proxy apps.

@@ Line 1: / Line 1: @@
 == SW4lite ==
 [[File:SW4-Comm.png| thumb| 300px| right|Figure 1. The communication pattern of SW4lite proxy app.]]
-[[File:PREMA SW4.png| thumb| 300px| right|Figure 2. The modified communication pattern of SW4lite proxy app to work with PREMA .]]
+[[File:PREMA SW4.png| thumb| 350px| right|Figure 2. The modified communication pattern of SW4lite proxy app to work with PREMA .]]
 In high-performance computing (HPC), proxy applications (“proxy apps”) are small, simplified codes that allow application developers to share important features of large applications without forcing collaborators to assimilate large and complex code bases. The Exascale Proxy Applications Project, part of the Exascale Computing Project (ECP), is a project where developers can share explore and share proxy apps.

@@ Line 1: / Line 1: @@
 == SW4lite ==
 [[File:SW4-Comm.png| thumb| 300px| right|Figure 1. The communication pattern of SW4lite proxy app.]]
 In high-performance computing (HPC), proxy applications (“proxy apps”) are small, simplified codes that allow application developers to share important features of large applications without forcing collaborators to assimilate large and complex code bases. The Exascale Proxy Applications Project, part of the Exascale Computing Project (ECP), is a project where developers can share explore and share proxy apps.
@@ Line 24: / Line 25: @@
 To achieve this we have added two more steps to the communication pattern, one for each direction. The idea is that the communication in each direction begins with the receiver neighbor requesting
 the data to be sent to it when it's ready to receive them. The sender will send the data when it's ready to do so. In this way, we guarantee that both neighbors' data are consistent after the first step
 of communication in each direction. The requests for the second and fourth steps are implicit as they are received as part of the actual data sent in the first and third steps.
 == MPI Times ==

@@ Line 11: / Line 11: @@
 The proxy starts by decomposing the original 2D grid into a number of partitions equal to the number of available processes. Each processor is assigned one equally sized partition of the grid, and thus
 the processors can be thought to be logically positioned in a 2D grid.  Next, some preprocessing takes place on these partitions that includes some
-data sharing between them. Once this step completes an iterative process starts consisting of computations intercepted by two cycles of neighbor-to-neighbor communication per iteration. The communication pattern of each cycle is as follows: each processor sends a portion of the partiton it holds to its left neighbor and waits to receive the respective data from its right neighbor. Once the respective data are received, the same pairs of processors share data in the opposite direction. Next, the same process takes place for the y-axis, each processor sends another portion of its data to its bottom neighbor and waits to receive the respective data from its top neighbor, and then they communicate in the opposite direction. Processors located in the edges of the grid only send/receive data to/from their remaining neighbors. Figure 1 shows the communication pattern schematically.
+data sharing between them. Once this step completes an iterative process starts consisting of computations intercepted by two cycles of neighbor-to-neighbor communication per iteration. The communication pattern of each cycle is as follows: each processor sends a portion of the partition it holds to its left neighbor and waits to receive the respective data from its right neighbor. Once the respective data are received, the same pairs of processors share data in the opposite direction. Next, the same process takes place for the y-axis, each processor sends another portion of its data to its bottom neighbor and waits to receive the respective data from its top neighbor, and then they communicate in the opposite direction. Processors located in the edges of the grid only send/receive data to/from their remaining neighbors. Figure 1 shows the communication pattern schematically.
 == MPI Times ==

@@ Line 273: / Line 273: @@
 {| class="wikitable"
-! #Cores !! MPI (s) !! PREMA
+|-
 |-
 |120  || 566.615 ||450.271

@@ Line 283: / Line 283: @@
 |750  || 107.271  ||84.8418
 |-
-|1000 || 94.442 ||64.5786
+|1000 || 69.442 ||64.5786
 |-
 |1250 || 60.2811  ||54.3832

@@ Line 270: / Line 270: @@
 |3.58
 |2.45
 |}

@@ Line 320: / Line 320: @@
 |2.19
 |1.53
 |}