Added a MPI rank filter to reduce the number of traced processes.

README.md

@@ -31,6 +31,14 @@ The LOGDIR variable may be used to specify another directory for the log files:
 ```
   LOGDIR=my_log_dir mpirun [MPI OPTIONS] ./strace-wrapper.sh ./my_app [APP OPTIONS]
 ```
+#### Filtering MPI ranks
+For MPI programs running with large number of processes the number of traced
+processes may have to be narrowed down. The RANK_FILTER variable allows to
+specify a regex pattern which is matched agains the MPI rank number. Only
+processes with ranks matching this regex will be traced.
+```
+  RANK_FILTER='[0-4]' mpirun [MPI OPTIONS] ./strace-wrapper.sh ./my_app [APP OPTIONS]
+```
 
 
 #### Analyzing Traces

strace-wrapper.sh

@@ -15,4 +15,11 @@ if ! test -d $LOGDIR ; then
   mkdir -p $LOGDIR
 fi
 LOGFILE="$LOGDIR/${MPI_RANK:+r${MPI_RANK}-}$(hostname).$$.strace"
-strace -f -r -T -o "$LOGFILE" "$@"
+
+
+if  ! test -z $MPI_RANK  &&  ! test -z $RANK_FILTER  &&  ! [[ $MPI_RANK =~ $RANK_FILTER ]] ; then
+  echo "# Rank $MPI_RANK not traced" > $LOGFILE
+  "$@"
+else
+  strace -f -r -T -o "$LOGFILE" "$@"
+fi