From bf944c0e7c257c68d4494ab01307ddba423008ee Mon Sep 17 00:00:00 2001
From: Pedro Gonnet <pedro.gonnet@durham.ac.uk>
Date: Fri, 12 Jul 2013 13:26:11 +0000
Subject: [PATCH] fix some timing bugs with the parallel particle sort.
Former-commit-id: c258689b9f119467d89135048c68fd24d65261dc
---
src/space.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/src/space.c b/src/space.c
index 5afd39f54c..dcf8a0422f 100644
--- a/src/space.c
+++ b/src/space.c
@@ -343,9 +343,10 @@ void space_rebuild ( struct space *s , double cell_max ) {
void parts_sort ( struct part *parts , struct xpart *xparts , int *ind , int N , int min , int max ) {
struct {
- int i, j, min, max, ready;
+ int i, j, min, max;
+ volatile int ready;
} qstack[space_qstack];
- volatile int first, last, waiting;
+ volatile unsigned int first, last, waiting;
int pivot;
int i, ii, j, jj, temp_i, qid;
@@ -363,7 +364,7 @@ void parts_sort ( struct part *parts , struct xpart *xparts , int *ind , int N ,
first = 0; last = 1; waiting = 1;
/* Parallel bit. */
- #pragma omp parallel default(shared) private(pivot,i,ii,j,jj,min,max,temp_i,qid,temp_xp,temp_p)
+ #pragma omp parallel default(none) shared(first,last,waiting,qstack,parts,xparts,ind) private(pivot,i,ii,j,jj,min,max,temp_i,qid,temp_xp,temp_p)
{
/* Main loop. */
@@ -374,7 +375,7 @@ void parts_sort ( struct part *parts , struct xpart *xparts , int *ind , int N ,
qid = atomic_inc( &first ) % space_qstack;
/* Wait for the interval to be ready. */
- while ( waiting > 0 && atomic_cas( &qstack[qid].ready , 1 , 0 ) != 1 );
+ while ( waiting > 0 && atomic_cas( &qstack[qid].ready , 1 , 1 ) != 1 );
/* Broke loop for all the wrong reasons? */
if ( waiting == 0 )
@@ -385,6 +386,7 @@ void parts_sort ( struct part *parts , struct xpart *xparts , int *ind , int N ,
j = qstack[qid].j;
min = qstack[qid].min;
max = qstack[qid].max;
+ qstack[qid].ready = 0;
// printf( "parts_sort_par: thread %i got interval [%i,%i] with values in [%i,%i].\n" , omp_get_thread_num() , i , j , min , max );
/* Loop over sub-intervals. */
@@ -425,6 +427,7 @@ void parts_sort ( struct part *parts , struct xpart *xparts , int *ind , int N ,
/* Recurse on the left? */
if ( jj > i && pivot > min ) {
qid = atomic_inc( &last ) % space_qstack;
+ while ( atomic_cas( &qstack[qid].ready , 0 , 0 ) != 0 );
qstack[qid].i = i;
qstack[qid].j = jj;
qstack[qid].min = min;
@@ -448,6 +451,7 @@ void parts_sort ( struct part *parts , struct xpart *xparts , int *ind , int N ,
/* Recurse on the right? */
if ( jj+1 < j && pivot+1 < max ) {
qid = atomic_inc( &last ) % space_qstack;
+ while ( atomic_cas( &qstack[qid].ready , 0 , 0 ) != 0 );
qstack[qid].i = jj+1;
qstack[qid].j = j;
qstack[qid].min = pivot+1;
--
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