SLUB: Remove checks for MAX_PARTIAL from kmem_cache_shrink (fcda3d89) · Commits · 戴 / test

The MAX_PARTIAL checks were supposed to be an optimization. However, slab shrinking is a manually triggered process either through running slabinfo or by the kernel calling kmem_cache_shrink. If one really wants to shrink a slab then all operations should be done regardless of the size of the partial list. This also fixes an issue that could surface if the number of partial slabs was initially above MAX_PARTIAL in kmem_cache_shrink and later drops below MAX_PARTIAL through the elimination of empty slabs on the partial list (rare). In that case a few slabs may be left off the partial list (and only be put back when they are empty). Signed-off-by:

Christoph Lameter <clameter@sgi.com>

mm/slub.c

+2 −7

Original line number	Original line	Diff line number	Diff line
	@@ -2500,15 +2500,11 @@ int kmem_cache_shrink(struct kmem_cache *s)
	slab_unlock(page);		slab_unlock(page);
	discard_slab(s, page);		discard_slab(s, page);
	} else {		} else {
	if (n->nr_partial > MAX_PARTIAL)
	list_move(&page->lru,		list_move(&page->lru,
	slabs_by_inuse + page->inuse);		slabs_by_inuse + page->inuse);
	}		}
	}		}

	if (n->nr_partial <= MAX_PARTIAL)
	goto out;

	/*		/*
	* Rebuild the partial list with the slabs filled up most		* Rebuild the partial list with the slabs filled up most
	* first and the least used slabs at the end.		* first and the least used slabs at the end.
	@@ -2516,7 +2512,6 @@ int kmem_cache_shrink(struct kmem_cache *s)
	for (i = s->objects - 1; i >= 0; i--)		for (i = s->objects - 1; i >= 0; i--)
	list_splice(slabs_by_inuse + i, n->partial.prev);		list_splice(slabs_by_inuse + i, n->partial.prev);

	out:
	spin_unlock_irqrestore(&n->list_lock, flags);		spin_unlock_irqrestore(&n->list_lock, flags);
	}		}

Admin message