/* ----------------------------------------------------------------------------- * * (c) The GHC Team 2008 * * Simple mark/sweep, collecting whole blocks. * * Documentation on the architecture of the Garbage Collector can be * found in the online commentary: * * https://gitlab.haskell.org/ghc/ghc/wikis/commentary/rts/storage/gc * * ---------------------------------------------------------------------------*/ #include "PosixSource.h" #include "Rts.h" #include "BlockAlloc.h" #include "Sweep.h" #include "Trace.h" void sweep(generation *gen) { bdescr *bd, *prev, *next; uint32_t i; W_ freed, resid, fragd, blocks, live; ASSERT(countBlocks(gen->old_blocks) == gen->n_old_blocks); live = 0; // estimate of live data in this gen freed = 0; fragd = 0; blocks = 0; prev = NULL; for (bd = gen->old_blocks; bd != NULL; bd = next) { next = bd->link; if (!(bd->flags & BF_MARKED)) { prev = bd; continue; } blocks++; resid = 0; for (i = 0; i < BLOCK_SIZE_W / BITS_IN(W_); i++) { if (bd->u.bitmap[i] != 0) resid++; } live += resid * BITS_IN(W_); if (resid == 0) { freed++; gen->n_old_blocks--; if (prev == NULL) { gen->old_blocks = next; } else { prev->link = next; } freeGroup(bd); } else { prev = bd; if (resid < (BLOCK_SIZE_W * 3) / (BITS_IN(W_) * 4)) { fragd++; bd->flags |= BF_FRAGMENTED; } bd->flags |= BF_SWEPT; } } gen->live_estimate = live; debugTrace(DEBUG_gc, "sweeping: %d blocks, %d were copied, %d freed (%d%%), %d are fragmented, live estimate: %ld%%", gen->n_old_blocks + freed, gen->n_old_blocks - blocks + freed, freed, blocks == 0 ? 0 : (freed * 100) / blocks, fragd, (unsigned long)((blocks - freed) == 0 ? 0 : ((live / BLOCK_SIZE_W) * 100) / (blocks - freed))); ASSERT(countBlocks(gen->old_blocks) == gen->n_old_blocks); }