[commit: ghc] master: Fix a missing getNewNursery(), and related cleanup (12ae1fa)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/12ae1fa51b2f59e37d6100359b494bee2192ef0a/ghc

>---------------------------------------------------------------

commit 12ae1fa51b2f59e37d6100359b494bee2192ef0a
Author: Simon Marlow <marlowsd at gmail.com>
Date:   Mon Jul 17 17:32:44 2017 +0100

    Fix a missing getNewNursery(), and related cleanup
    
    Summary:
    When we use nursery chunks with +RTS -n<size>, when the current nursery
    runs out we have to check whether there's another chunk available with
    getNewNursery().  There was one place we weren't doing this: the ad-hoc
    heap check in scheduleProcessInbox().
    
    The impact of the bug was that we would GC too early when using nursery
    chunks, especially in programs that used messages (throwTo between
    capabilities could do this, also hs_try_putmvar()).
    
    Test Plan: validate, also local testing in our application
    
    Reviewers: bgamari, niteria, austin, erikd
    
    Subscribers: rwbarton, thomie
    
    Differential Revision: https://phabricator.haskell.org/D3749


>---------------------------------------------------------------

12ae1fa51b2f59e37d6100359b494bee2192ef0a
 rts/Schedule.c   | 19 +++----------------
 rts/sm/Storage.h | 22 +++++++++++-----------
 2 files changed, 14 insertions(+), 27 deletions(-)

diff --git a/rts/Schedule.c b/rts/Schedule.c
index 7950785..8002ac3 100644
--- a/rts/Schedule.c
+++ b/rts/Schedule.c
@@ -993,8 +993,8 @@ scheduleProcessInbox (Capability **pcap USED_IF_THREADS)
     Capability *cap = *pcap;
 
     while (!emptyInbox(cap)) {
-        if (cap->r.rCurrentNursery->link == NULL ||
-            g0->n_new_large_words >= large_alloc_lim) {
+        // Executing messages might use heap, so we should check for GC.
+        if (doYouWantToGC(cap)) {
             scheduleDoGC(pcap, cap->running_task, false);
             cap = *pcap;
         }
@@ -1183,20 +1183,7 @@ scheduleHandleHeapOverflow( Capability *cap, StgTSO *t )
         }
     }
 
-    // if we got here because we exceeded large_alloc_lim, then
-    // proceed straight to GC.
-    if (g0->n_new_large_words >= large_alloc_lim) {
-        return true;
-    }
-
-    // Otherwise, we just ran out of space in the current nursery.
-    // Grab another nursery if we can.
-    if (getNewNursery(cap)) {
-        debugTrace(DEBUG_sched, "thread %ld got a new nursery", t->id);
-        return false;
-    }
-
-    return true;
+    return doYouWantToGC(cap);
     /* actual GC is done at the end of the while loop in schedule() */
 }
 
diff --git a/rts/sm/Storage.h b/rts/sm/Storage.h
index 2d69eee..aaa4442 100644
--- a/rts/sm/Storage.h
+++ b/rts/sm/Storage.h
@@ -25,17 +25,6 @@ void freeStorage(bool free_heap);
 void storageAddCapabilities (uint32_t from, uint32_t to);
 
 /* -----------------------------------------------------------------------------
-   Should we GC?
-   -------------------------------------------------------------------------- */
-
-INLINE_HEADER
-bool doYouWantToGC(Capability *cap)
-{
-    return (cap->r.rCurrentNursery->link == NULL ||
-            g0->n_new_large_words >= large_alloc_lim);
-}
-
-/* -----------------------------------------------------------------------------
    The storage manager mutex
    -------------------------------------------------------------------------- */
 
@@ -75,6 +64,17 @@ StgWord  countNurseryBlocks   (void);
 bool     getNewNursery        (Capability *cap);
 
 /* -----------------------------------------------------------------------------
+   Should we GC?
+   -------------------------------------------------------------------------- */
+
+INLINE_HEADER
+bool doYouWantToGC(Capability *cap)
+{
+    return ((cap->r.rCurrentNursery->link == NULL && !getNewNursery(cap)) ||
+            g0->n_new_large_words >= large_alloc_lim);
+}
+
+/* -----------------------------------------------------------------------------
    Allocation accounting
 
    See [Note allocation accounting] in Storage.c