Esempio n. 1
0
/* Full heap sanity check. */
static void checkFullHeap (rtsBool after_major_gc)
{
    nat g, n;

    for (g = 0; g < RtsFlags.GcFlags.generations; g++) {
        checkGeneration(&generations[g], after_major_gc);
    }
    for (n = 0; n < n_capabilities; n++) {
        checkNurserySanity(&nurseries[n]);
    }
}
Esempio n. 2
0
StgPtr
allocate (Capability *cap, W_ n)
{
    bdescr *bd;
    StgPtr p;

    TICK_ALLOC_HEAP_NOCTR(WDS(n));
    CCS_ALLOC(cap->r.rCCCS,n);
    if (cap->r.rCurrentTSO != NULL) {
        // cap->r.rCurrentTSO->alloc_limit -= n*sizeof(W_)
        ASSIGN_Int64((W_*)&(cap->r.rCurrentTSO->alloc_limit),
                     (PK_Int64((W_*)&(cap->r.rCurrentTSO->alloc_limit))
                      - n*sizeof(W_)));
    }

    if (n >= LARGE_OBJECT_THRESHOLD/sizeof(W_)) {
        // The largest number of words such that
        // the computation of req_blocks will not overflow.
        W_ max_words = (HS_WORD_MAX & ~(BLOCK_SIZE-1)) / sizeof(W_);
        W_ req_blocks;

        if (n > max_words)
            req_blocks = HS_WORD_MAX; // signal overflow below
        else
            req_blocks = (W_)BLOCK_ROUND_UP(n*sizeof(W_)) / BLOCK_SIZE;

        // Attempting to allocate an object larger than maxHeapSize
        // should definitely be disallowed.  (bug #1791)
        if ((RtsFlags.GcFlags.maxHeapSize > 0 &&
             req_blocks >= RtsFlags.GcFlags.maxHeapSize) ||
            req_blocks >= HS_INT32_MAX)   // avoid overflow when
                                          // calling allocGroup() below
        {
            heapOverflow();
            // heapOverflow() doesn't exit (see #2592), but we aren't
            // in a position to do a clean shutdown here: we
            // either have to allocate the memory or exit now.
            // Allocating the memory would be bad, because the user
            // has requested that we not exceed maxHeapSize, so we
            // just exit.
            stg_exit(EXIT_HEAPOVERFLOW);
        }

        ACQUIRE_SM_LOCK
        bd = allocGroup(req_blocks);
        dbl_link_onto(bd, &g0->large_objects);
        g0->n_large_blocks += bd->blocks; // might be larger than req_blocks
        g0->n_new_large_words += n;
        RELEASE_SM_LOCK;
        initBdescr(bd, g0, g0);
        bd->flags = BF_LARGE;
        bd->free = bd->start + n;
        cap->total_allocated += n;
        return bd->start;
    }

    /* small allocation (<LARGE_OBJECT_THRESHOLD) */

    bd = cap->r.rCurrentAlloc;
    if (bd == NULL || bd->free + n > bd->start + BLOCK_SIZE_W) {
        
        if (bd) finishedNurseryBlock(cap,bd);

        // The CurrentAlloc block is full, we need to find another
        // one.  First, we try taking the next block from the
        // nursery:
        bd = cap->r.rCurrentNursery->link;
        
        if (bd == NULL) {
            // The nursery is empty: allocate a fresh block (we can't
            // fail here).
            ACQUIRE_SM_LOCK;
            bd = allocBlock();
            cap->r.rNursery->n_blocks++;
            RELEASE_SM_LOCK;
            initBdescr(bd, g0, g0);
            bd->flags = 0;
            // If we had to allocate a new block, then we'll GC
            // pretty quickly now, because MAYBE_GC() will
            // notice that CurrentNursery->link is NULL.
        } else {
            newNurseryBlock(bd);
            // we have a block in the nursery: take it and put
            // it at the *front* of the nursery list, and use it
            // to allocate() from.
            //
            // Previously the nursery looked like this:
            //
            //           CurrentNursery
            //                  /
            //                +-+    +-+
            // nursery -> ... |A| -> |B| -> ...
            //                +-+    +-+
            //
            // After doing this, it looks like this:
            //
            //                      CurrentNursery
            //                            /
            //            +-+           +-+
            // nursery -> |B| -> ... -> |A| -> ...
            //            +-+           +-+
            //             |
            //             CurrentAlloc
            //
            // The point is to get the block out of the way of the
            // advancing CurrentNursery pointer, while keeping it
            // on the nursery list so we don't lose track of it.
            cap->r.rCurrentNursery->link = bd->link;
            if (bd->link != NULL) {
                bd->link->u.back = cap->r.rCurrentNursery;
            }
        }
        dbl_link_onto(bd, &cap->r.rNursery->blocks);
        cap->r.rCurrentAlloc = bd;
        IF_DEBUG(sanity, checkNurserySanity(cap->r.rNursery));
    }
    p = bd->free;
    bd->free += n;

    IF_DEBUG(sanity, ASSERT(*((StgWord8*)p) == 0xaa));
    return p;
}