示例#1
0
文件: Storage.c 项目: adgalad/ghc
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;
}
示例#2
0
文件: Storage.c 项目: adgalad/ghc
StgPtr
allocatePinned (Capability *cap, W_ n)
{
    StgPtr p;
    bdescr *bd;

    // If the request is for a large object, then allocate()
    // will give us a pinned object anyway.
    if (n >= LARGE_OBJECT_THRESHOLD/sizeof(W_)) {
        p = allocate(cap, n);
        Bdescr(p)->flags |= BF_PINNED;
        return 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_)));
    }

    bd = cap->pinned_object_block;
    
    // If we don't have a block of pinned objects yet, or the current
    // one isn't large enough to hold the new object, get a new one.
    if (bd == NULL || (bd->free + n) > (bd->start + BLOCK_SIZE_W)) {

        // stash the old block on cap->pinned_object_blocks.  On the
        // next GC cycle these objects will be moved to
        // g0->large_objects.
        if (bd != NULL) {
            // add it to the allocation stats when the block is full
            finishedNurseryBlock(cap, bd);
            dbl_link_onto(bd, &cap->pinned_object_blocks);
        }

        // We need to find another block.  We could just allocate one,
        // but that means taking a global lock and we really want to
        // avoid that (benchmarks that allocate a lot of pinned
        // objects scale really badly if we do this).
        //
        // So first, we try taking the next block from the nursery, in
        // the same way as allocate(), but note that we can only take
        // an *empty* block, because we're about to mark it as
        // BF_PINNED | BF_LARGE.
        bd = cap->r.rCurrentNursery->link;
        if (bd == NULL) { // must be empty!
            // The nursery is empty, or the next block is non-empty:
            // allocate a fresh block (we can't fail here).

            // XXX in the case when the next nursery block is
            // non-empty we aren't exerting any pressure to GC soon,
            // so if this case ever happens then we could in theory
            // keep allocating for ever without calling the GC. We
            // can't bump g0->n_new_large_words because that will be
            // counted towards allocation, and we're already counting
            // our pinned obects as allocation in
            // collect_pinned_object_blocks in the GC.
            ACQUIRE_SM_LOCK;
            bd = allocBlock();
            RELEASE_SM_LOCK;
            initBdescr(bd, g0, g0);
        } else {
            newNurseryBlock(bd);
            // we have a block in the nursery: steal it
            cap->r.rCurrentNursery->link = bd->link;
            if (bd->link != NULL) {
                bd->link->u.back = cap->r.rCurrentNursery;
            }
            cap->r.rNursery->n_blocks -= bd->blocks;
        }

        cap->pinned_object_block = bd;
        bd->flags  = BF_PINNED | BF_LARGE | BF_EVACUATED;

        // The pinned_object_block remains attached to the capability
        // until it is full, even if a GC occurs.  We want this
        // behaviour because otherwise the unallocated portion of the
        // block would be forever slop, and under certain workloads
        // (allocating a few ByteStrings per GC) we accumulate a lot
        // of slop.
        //
        // So, the pinned_object_block is initially marked
        // BF_EVACUATED so the GC won't touch it.  When it is full,
        // we place it on the large_objects list, and at the start of
        // the next GC the BF_EVACUATED flag will be cleared, and the
        // block will be promoted as usual (if anything in it is
        // live).
    }

    p = bd->free;
    bd->free += n;
    return p;
}
示例#3
0
文件: Threads.c 项目: Julek/gestalt
/* ---------------------------------------------------------------------------
 * Getting & setting the thread allocation limit
 * ------------------------------------------------------------------------ */
HsInt64 rts_getThreadAllocationCounter(StgPtr tso)
{
    // NB. doesn't take into account allocation in the current nursery
    // block, so it might be off by up to 4k.
    return PK_Int64((W_*)&(((StgTSO *)tso)->alloc_limit));
}