From bc72b5d248842ff3e091bf4d168352f114bfee97 Mon Sep 17 00:00:00 2001
From: Matthieu Schaller <schaller@strw.leidenuniv.nl>
Date: Sun, 22 Mar 2020 00:27:48 +0100
Subject: [PATCH] Solve the dining philosopher problem in the locking of the
cells' multipoles
---
src/runner_doiact_grav.c | 30 +++++++++++++++++++++---------
1 file changed, 21 insertions(+), 9 deletions(-)
diff --git a/src/runner_doiact_grav.c b/src/runner_doiact_grav.c
index 3b8611adb1..9a998907d7 100644
--- a/src/runner_doiact_grav.c
+++ b/src/runner_doiact_grav.c
@@ -1357,9 +1357,15 @@ static INLINE void runner_dopair_grav_mm_symmetric(struct runner *r,
cj->grav.ti_old_multipole, cj->nodeID, ci->nodeID, e->ti_current);
#endif
- /* Lock the multipoles */
- lock_lock(&ci->grav.mlock);
- lock_lock(&cj->grav.mlock);
+ /* Lock the multipoles
+ * Note we impose a hierarchy to solve the dining philosopher problem */
+ if (ci < cj) {
+ lock_lock(&ci->grav.mlock);
+ lock_lock(&cj->grav.mlock);
+ } else {
+ lock_lock(&cj->grav.mlock);
+ lock_lock(&ci->grav.mlock);
+ }
/* Let's interact at this level */
gravity_M2L_symmetric(&ci->grav.multipole->pot, &cj->grav.multipole->pot,
@@ -1381,9 +1387,9 @@ static INLINE void runner_dopair_grav_mm_symmetric(struct runner *r,
* @param ci The #cell with field tensor to interact.
* @param cj The #cell with the multipole.
*/
-static INLINE void runner_dopair_grav_mm_nonsym(
- struct runner *r, struct cell *restrict ci,
- struct cell *restrict cj) {
+static INLINE void runner_dopair_grav_mm_nonsym(struct runner *r,
+ struct cell *restrict ci,
+ struct cell *restrict cj) {
/* Some constants */
const struct engine *e = r->e;
@@ -1416,9 +1422,15 @@ static INLINE void runner_dopair_grav_mm_nonsym(
cj->grav.ti_old_multipole, cj->nodeID, ci->nodeID, e->ti_current);
#endif
- /* Lock the multipoles */
- lock_lock(&ci->grav.mlock);
- lock_lock(&cj->grav.mlock);
+ /* Lock the multipoles
+ * Note we impose a hierarchy to solve the dining philosopher problem */
+ if (ci < cj) {
+ lock_lock(&ci->grav.mlock);
+ lock_lock(&cj->grav.mlock);
+ } else {
+ lock_lock(&cj->grav.mlock);
+ lock_lock(&ci->grav.mlock);
+ }
/* Let's interact at this level */
gravity_M2L_nonsym(&ci->grav.multipole->pot, multi_j, ci->grav.multipole->CoM,
--
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